www.riscos.com Technical Support: RISC OS 3 User Guide

RISC OS 3.7 User Guide

19 - Paint

Paint is a pixel-based picture editor; you can use it to 'paint' coloured images by applying colours to an area with a variety of brushes and painting tools.

You will probably find that the easiest way of learning Paint is to read through Basic ideas and then work through the Paint tutorial which follows before coming back to the Paint reference section.

Starting Paint

Paint is in the Apps icon bar directory display. To start Paint and create a new sprite double-click on the !Paint icon to install it on the icon bar then click on the Paint icon bar icon to display the Create new sprite window.

Fill in the details for your new sprite and click on OK. It's probably best to follow the Paint Tutorial if you don't already know how to do this.

Alternatively, edit an existing sprite file by dragging its file icon to the Paint icon on the icon bar, or by double-clicking on it.

Basic ideas

The pictures produced by Paint are called sprites and are represented by the file icon shown on the left.

The important difference between Paint and Draw is that, unlike Draw, Paint knows nothing about 'objects' such as rectangles and circles; all it knows is the colour of each pixel in a sprite. Although you can paint regular shapes, you cannot then select them in order to delete, move or resize them.

When you export (save) a sprite from Paint into Draw, this remains true: regular shapes forming part of the sprite cannot be edited like Draw objects. The whole sprite becomes a single object in your Draw diagram; you can move or resize it, but not otherwise edit it.

Choosing colours in Paint

Paint can create and edit pictures in any RISC OS screen mode: 16 million colours, 32 thousand colours, 256 colours, 16 colours, 4 greys and black and white. There are two different ways of choosing colours in a sprite.

• Sprites created in up to 256 colours use a Colours window, familiar to users of previous versions of RISC OS. The Paint tutorial) uses this method.
• 32-thousand and 16-million colour sprites make use of the Colours window described in Using colour in applications.

Creating sprite files compatible with earlier versions of RISC OS

If you want to create sprite files that are compatible with earlier versions of RISC OS, make sure you choose a sprite type that has an equivalent old-type mode number.

Paint reference section

This section tells you in detail how to use Paint, and outlines the terms, concepts and basic techniques for creating and editing sprites. For a brief introduction to Paint and sprites, see the section Basic ideas.

Paint has several windows with specialised functions

• Create new sprite window - Use this to set up a new sprite.
• Sprite file window - Think of this as a sort of Paint 'directory'; it can contain more than one sprite.
• Sprite window - This is like any other application window (e.g. a Draw window): It contains the current file (in this case, a sprite) you're editing.
• Colours window - You use this in conjunction with the tools window to change the colour of pixels in a sprite.
• Paint tools window - This contains the different tools you use to edit a sprite's pixels.

Creating a new sprite

To create a new sprite click on the Paint icon on the icon bar. The windows shown below will open. You define the sprite's attributes in the Create new sprite window.

The table below tells you what all the options in this dialogue box mean.

To:

• Name a new sprite: Fill in the Name box. Sprite names can be up to 12 characters long.
• Allow a sprite to use transparent pixels, as well as coloured ones: Switch the Mask option on. This defines an extra 'colour' in the Colours window. Pixels painted in this colour are transparent.
• Define the size of the sprite in pixels: Fill in the Width and Height boxes. The default is the size of the current display.
  You can also click on the resize arrows at the bottom of the window.
                   
  Note that for very large sprites (height greater than 1024 pixels) some Paint tools may not work properly (e.g. Replace colour).
• Change the pixel size: Choose from 45, 90 and 180 dots per inch (dpi). Larger dpi settings give smaller pixels (hence a smaller canvas).
• Set the number of colours in the sprite: Choose from 2, 4, 16, 256, 32K or 16M. Usually the same as in the current display mode.
• Define whether the sprite uses a palette: Choose colour for backward compatibility with earlier versions of RISC OS, mono for grey shades or none for the default palette. You can't set a palette in 32K and 16M modes.
  Colour sprites with a palette have white as colour 0; mono sprites have black as colour 0. Mono palettes may not display correctly on earlier operating systems.

Note: You can normally ignore the colours (mode) box. If there's a number shown here, the sprite is created as an old format sprite. If it's blank, the sprite created is a new format sprite.

Handling sprite files

It's easy to become confused over the difference between sprites and sprite files. This section shows you how to create and manipulate sprites and sprite files.

If you prefer, you can keep just one sprite in each sprite file. However, you can store many sprites in a sprite file.

To:

• Open a Sprite file window: Double-click on a sprite file icon, or drag its icon onto Paint's icon bar icon. Shows all sprites in the sprite file at actual size if possible.
• Save a sprite file (and all the sprites it contains): Click Menu over the Sprite file window and drag the Save/Save as icon to a directory display. You can save it under a different name if you wish.
  Note: If you drop the Save/Save as icon onto another Sprite file window instead, any existing sprites in that window with the same name will be replaced.
• Create a new sprite in a Sprite file window: Click Menu over the Sprite file window and fill in the New sprite/Create new sprite box. You can also double-click on a blank part of the sprite file window.
• Change the Sprite file window display: Click Menu and choose one of the Display options. This is rather like changing directory displays.
• See information about Paint or the sprite file: Click Menu and display the Misc/Info or Misc/File box. File gives you the sprite file's name, number of sprites and size in bytes.
• See how the sprite would look if used as an icon: Choose Misc/Use desktop colours. This option is ignored if the sprite has its own palette.

Manipulating sprites within a sprite file

You can perform various operations on the sprites in a Sprite file window:

To:

• Open a sprite for editing: Double-click on its picture in the Sprite file window. You can also open other views of the same sprite, rather like the New view option in Draw, at different zoom settings.
• Copy a sprite within a sprite file: Click Menu over the sprite's picture in the sprite file and enter a new name in the Sprite/Copy box. You can also enter a new name in the Sprite/Save as box and drag the icon onto the Sprite file window.
• Rename a sprite: Use the Sprite/Rename box from the sprite file window menu.
• Delete a sprite from a sprite file: Click Menu over the sprite's picture in the sprite file window and choose Sprite/Delete. Don't delete the last sprite from a sprite file, or you won't be able to save the sprite file.
• Save a sprite from a sprite file: Click Menu over the sprite's picture in the sprite file window and drag the Sprite/Save/Save as icon.

Adding an existing sprite to a sprite file

There are three ways of adding an existing sprite to a different sprite file.

• Drag a sprite file icon and drop it onto the destination Sprite file window. If the source sprite file contains many sprites, they're all added to the destination Sprite file window. Sprites with the same name will be overwritten.
• Click Menu over a sprite's picture in the source Sprite file window and drag the Sprite '>name'/Save/Save as icon onto the destination Sprite file window.
• Click Menu over an open Sprite file window and drag the Sprite/Save/Save as icon onto the destination Sprite file window.

Handling JPEG images

You can also use Paint to edit JPEG images. To load a JPEG file into Paint, drag the JPEG file icon onto Paint's icon bar icon.

If you drag a JPEG file onto Paint's icon, a Sprite file window, a sprite window and a colours window will all open, ready for you to edit the image.

Notes:

• Paint may automatically perform some dithering when you load a JPEG file. You can often get a better quality sprite by using ChangeFSI to process the JPEG file and saving the resulting sprite into Paint.
• Once you've loaded a JPEG file into paint, you cannot use Paint to change it back into a JPEG file. You can use ChangeFSI to do this, though - see the section Output options.
• If you double-click on a JPEG file, it will be loaded automatically into ChangeFSI. This may not happen if your computer is low on memory. You can display a JPEG using less memory by loading it into Draw.

Choosing and using colours

You use the Colours window to choose the colour that you are painting with. There is a separate Colours window for each sprite. To open the Colours window (if it's not already displayed) click Menu on the sprite window and choose Paint/Show colours.

There are in fact two different Colours windows. See the section Using colour in applications for details on the second of these two windows.

Choosing a colour

For sprites with up to 256 colours, the current colour is highlighted in the colours window, and shows the colour number. The colours shown are the shades that can be displayed in the current screen mode. These may be an approximation to the actual palette of the sprite. For more information see Mixing new colours using a palette).

Finding out the colour of an individual pixel

Another way to choose a colour is to point at a pixel in the sprite window, click Menu and choose Paint/Select colour. You can use this method to find out exactly which colour has been used to paint the pixel.

Making the Colours window smaller

You can make the Colours window smaller by clicking Menu over the sprite window and choosing Paint/Small colours. This toggles the size of the sprite colours window. The colours window must be open for this to take effect. The small colours window takes less screen space than the large one. This is particularly valuable in 256-colour modes.

Using a transparent mask

If a sprite with up to 256 colours has a mask, an extra, special colour is shown in the bottom lefthand corner of the sprite colours window as a shaded square.

If a 32-thousand or 16-million colour sprite has a mask, you will be able to select it by choosing None in the bottom of the Colours window.

Adding a mask

If a sprite doesn't have a mask, you can add one by clicking Menu over the sprite window and choosing Edit/Mask.

For more information about using masks see the section Painting with the mask of a sprite.

Applying colours using logical operators

There are four different ways in which you can apply colour to a sprite, using the Set, OR, AND and EOR buttons in the tools window (the tools themselves are described in the section Using Paint's tools).

Set causes the colour itself to be painted into the sprite. The remaining three styles cause the indicated logical operation to be applied between the colour number of the pixel on the screen and that selected in the Colours window.

For example, if you choose EOR, spraying with colour 11 (binary 1011) onto an area that is currently colour 12 (binary 1100) will produce pixels in colour 7 (binary 0111). For a description of logical operations, see the BBC BASIC Reference Manual.

• OR sets more pixels towards the higher numbered colours in the palette.
• AND sets more pixels towards the lower numbered colours in the palette.
• EOR maintains a wider variety of colours than OR or AND.

You can set a sprite's palette by dropping a palette file onto the sprite window. See the section Saving a palette for more about this.

The most interesting effects are achieved when spraying over a range of existing colours, or drawing overlapping filled shapes. Experiment for yourself!

Mixing new colours using a palette

For 32K and 16M-colour sprites, you can paint a pixel in virtually any colour by choosing it from the Colours window. However, sprites which use 256 colours or less only have a limited range of colours to choose from. In such cases, if a sprite has a palette, you can use it to mix new colours.

Giving a sprite a palette

If a sprite doesn't have its own palette, and you want to give it one, click Menu over the sprite window and choose Edit/Palette. Sprites which don't have their own palettes use the default desktop palette for a given mode (unless Display/Use desktop colours is off, in which case the old BBC colours are used).

By default, when you create a new sprite, it is given a palette.

Notes:

• If you want to use a sprite as a tiled backdrop, it should not have a palette.
• If you intend to export a sprite to Draw, you should give it a palette (otherwise it won't retain the colours you give it).

Redefining colours (editing a palette)

This method works for all sprites with up to 16 colours, and with 256-colour sprites with true-colour palettes.

1. Click on the colour in the Colours window that you want to change.
2. Click Menu over the sprite window and display the Paint/Edit palette/Edit colour box.
3. Mix a new colour and click on OK to redefine the Colours window.

256-colour sprites with colour palettes

The one exception when mixing new colours is a 256-colour sprite with a colour palette (as opposed to a true-colour palette). In order to be able to edit such a sprite's palette, you need to save its palette back into the sprite window (see below). Alternatively, you can create a 256-greyscale sprite and edit its palette.

Saving a palette

1. Click Menu over the sprite window and display the Save/Palette box:
                   Drag the Save as icon to a directory display.

If you want to use the same palette in another sprite, drag this palette file onto the new sprite window. This modifies the palette used by the sprite.

Creating an extended colour fill (ECF)

To create an ECF, click Menu over the sprite window and choose Paint/Select ECF. This leads to a dialogue box which you can use to extract the bottom lefthand pixels of a named sprite as an ECF pattern. ECFs are patterns that you can use in place of a colour, and are added to the sprite palette, below the plain colours.

You can't define an ECF for sprites with more than 256 colours. You can define up to four ECFs for each sprite.

Zooming in and out (scaling a sprite window)

To scale the size of a sprite window to make it easier to edit, press Menu over the sprite window and set a zoom factor in the Zoom/Magnifier dialogue box.

The magnification only changes the size at which the sprite is displayed in the window; the actual definition, height and width are not affected. The magnification is expressed as a ratio; for example 2:1 means twice normal size, 3:4 means three-quarters of normal size, and so on. You can change the ratio either by clicking on the up and down arrows, or by typing in a new value at the caret.

Using a grid

You can use a grid to see the boundaries between individual pixels in a sprite:

To:

• Toggle the grid on or off: Press Menu over the sprite window and choose Grid.
• Change the grid's display colour: Press Menu over the sprite window and choose a colour from the Grid submenu.

The grid is displayed at different magnifications for sprites of different sizes (so for example, you might only see the grid at zooms of 3:1 or higher for one sprite, but at zooms of 5:1 or higher for another).

Using Paint's tools

You choose tools from the Paint tools window to edit a sprite (or JPEG file).

If, when you open a sprite for editing, the tools window doesn't appear on the screen, you can display it by clicking Menu on the sprite window and choosing Paint/Show tools.

The top section of the window shows the tools. The currently-selected tool is highlighted and its name shown below the icons.

Below this are buttons used to define how colour will be applied to the image. When certain tools are selected, an extension may appear at the bottom of the tools window for setting extra parameters.

Choosing tools

To use a tool to edit a sprite:

1. Click on the tool in the Paint tools window.
2. If you want, set or change any parameters, such as the size of the spray or brush to be used.
3. Choose a colour from the Colours window.
4. Move the mouse to the sprite window, and apply the tool as described below.

For operations such as drawing lines and rectangles, you can click Adjust instead of Select. This moves the point you just set to the current position.

While some operations are in progress, a skeleton line or area is shown.

You can cancel any of the sequences of operations described below by clicking again on the current tool in the Paint tools window.

Function	Tool to choose
	Paint a pixel: Set/clear pixels: Click Adjust to clear a pixel to colour 0. Drag the pointer to paint many pixels.
	Spray pixels in an area around the pointer position: Spray can: Set the spray Density and Radius at the bottom of the tools window. Spray with Adjust to clear pixels to colour 0.
	Paint another sprite into the current one: Use sprite as brush: See Using a sprite as a brush.
	Replace one colour with another (flood fill): Replace colour Local changes all touching pixels of the same colour. Global changes all similarly- coloured pixels in the sprite.
	Copy a rectangular block from one part of a sprite to another: Copy block (switch Local on): Drag a select box around the block to be copied. Click to position the copied block.
	Save (export) a rectangular block of a sprite: Copy block (switch Export on): Drag a select box around the block to be copied. Drag the Save as icon to a directory or sprite file.
	Move a rectangular block from one part of a sprite to another: Move block (switch Local on). Works in the same way as Copy block (Local), but area left behind is filled with colour 0.
	Save (export) a rectangular block of a sprite: Move block (switch Export on). Works in the same way as Copy block (Export).
	Move the entire sprite within the sprite window: Move whole sprite. Drag pointer to new position in sprite window. Any parts of image which move outside window are lost.
	Paint a solid line of pixels: Click at each end of the line.
	Paint a solid triangle : Filled triangles. Click on each corner of the triangle.
	Paint an outline or solid rectangle: Rectangle outlines or Filled rectangles. Click on opposite corners of the rectangle.
	Paint an outline or solid parallelogram: Parallelogram outlines or Filled parallelograms. Click on three corners of the parallelogram.
	Paint an outline or solid circles: Circle outlines or Filled circles. Click at the centre, then on the circumference.
	Paint an outline or solid ellipse: Ellipse outlines or Filled ellipses . Click at the centre. Second click defines the width.
	Paint an arc or solid circular segment: Circle outline sections or Filled circle segments. Click to define the centre of a circle, then click at each end of the arc.
	Paint a solid circular sector: Filled circle sectors. Click to define the centre of a circle, then click at each end of the arc.
	Paint a text line onto a sprite: Insert text. Enter the text, character sizes (pixels) and spacing (pixels) in the tools window. Click to define centre of text line. Only System font is available.

Using a sprite as a brush

Here's a bit more on using a sprite as a brush. There are a couple of examples of using this tool in the Paint tutorial.

To:

• Use one of the default brush shapes: Type one of the default names into the Name box and click on OK. You can use square, triangle, circle or brush.
• Use one of your own sprites as a brush: Open the Sprite file window and type the sprite's name in the Name box and click on OK.
• Use just the outline of the source sprite: Switch Shape on and click on OK. Pixels in brush sprite which are not transparent are set to the current colour.
• Paint with the full coloured sprite image: Switch Shape off and click on OK.
• Use the source sprite at a different size: Set the X scale and Y scale multipliers and click on OK. This is useful for using the same source sprite at different sizes.

Changing a sprite's size, shape and orientation

You can perform many operations on a sprite using Paint's Edit menu. Click Menu over a sprite window and choose from the Paint/Edit submenu.

Function and option to choose:

• Invert a sprite vertically about its centre: Flip vertically
• Invert a sprite horizontally about its centre: Flip horizontally
• Rotate a sprite about its centre: Rotate. Enter the angle in the Rotation box.
                     
  The sprite size changes if you rotate for angles other than multiples of 90 degrees unless the sprite has an even aspect ratio and pixel height/width.
• Scale the sprite horizontally or vertically: Scale x or Scale y
                     
  Enter the scale factor in the Factor box. Negative scale factors are not allowed.
• Slant the sprite horizontally: Shear
                     
  Enter the shear factor in the Shear box.
  The top row of pixels is moved right. The rows in between are moved proportionally. The factor is the tangent of the angle you want to shear by. A factor of 1 slants the sprite 45 degrees.
• Add or delete rows or columns from the top or right edge of a sprite: Adjust size.
                     
  Use the arrows in the Sprite size box, or fill in the Width and Height boxes, and click on OK.
• Add or delete columns at the pointer position: Insert columns, Insert rows, Delete columns, Delete rows
                     
  Inserted rows or columns are filled with colour 0.
  Columns are deleted to the right of the pixel over which you clicked Menu. Rows are deleted upwards. See below for more information.

More on adding and deleting rows and columns

Enter the number of rows or columns in the How many? box and click Select or press Return. Alternatively, without passing over a menu, move the pointer over the sprite window to change the size of the highlighted area that appears and click when the How many? box shows the right number.

Deleting the column of pixels on the righthand edge of a sprite can be difficult. Increasing the zoom scale can help, or you can delete the last column separately by using Adjust size to decrease the width by 1 column.

Taking screen snapshots

You can use Paint to save part of the screen as a sprite file (this is how the pictures of menus, windows and so on were produced in this User Guide). Start snapshot by choosing Snapshot from the icon bar menu. This displays the snapshot dialogue box.

Function/Procedure:

• Take a snapshot of the whole screen: Tick the Grab whole screen box and click on OK. Drag the resulting Save as icon to a directory display.
• Take a snapshot of part of the screen:
    Switch Grab whole screen off and click on OK. Then drag a select box using the camera pointer that appears round the area you want to snapshot. Drag the resulting Save as icon to a directory display.
• Set a delay before the snapshot is taken: Switch on User defined in the Delay before snapshot area and enter the delay in seconds. Then take the snapshot as above. This allows you to take shots of transient items (like menus) while the timer is counting down. You can position menus etc. in the snapshot area you defined.

Printing a sprite

Before you can print a sprite, you must have the Printer manager loaded. There are two ways you can print a sprite:

• Click Menu over the sprite's picture in the Sprite file window and display the Sprite/Print/Print sprite dialogue box.
• Click Menu over the sprite window and display the Misc/Print/Print sprite dialogue box.

The dialogue box is the same in both cases. The exact contents of the dialogue box depend on the printer driver in use, but it typically allows you to choose the orientation (Portrait or Landscape) scaling, and position on the paper.

Scale allows you to change the proportions of the printed image. Setting both x and y to 1:2 will produce a half-sized image.

Corner defines where on the printed page the image will be printed. The default settings define the edge of the printable page for your printer. Changing these settings will move the printing position of the image.

Saving Paint features in a Desktop boot file

You may want to change some aspects of the way new Paint windows appear when you first open them. For example, a new window normally opens with Zoom magnification set to 1:1, but you may prefer to have the Zoom option set to 2:1 each time you start Paint.

You can set features of this type by setting up Paint as you want to use it, then save these features by creating a Desktop boot file. Instructions on how to create a Desktop boot file are given in the section Configuring applications.

There are several features of Paint that you can set before saving a Desktop boot file, so that they are set up the way you want them each time you switch on.

Types of sprite that can be created by Paint

This table gives the various types of sprite that can be created by Paint. It shows if

• they are backward compatible with RISC OS 3.1 and earlier versions of the operating system - they have a mode number
• they can be modified by Paint.

You can select these combinations using the Create new sprite window. See page 297 for more information.

>Number of colours	Dots per inch	Equivalent old mode number
Two	90x90	25
Two	45x45	not backward compatible
Two	90x45	0
Two	Other combinations	not backward compatible
Four	90x90	26
Four	45x45	1
Four	90x45	8
Four	Other combinations	not backward compatible
Sixteen	90x90	27
Sixteen	45x45	9
Sixteen	90x45	12
Sixteen	Other combinations	not backward compatible
256	90x90	28
256	45x45	13
256	90x45	15
256	Other combinations	not backward compatible
32K	All combinations	not backward compatible
16M	All combinations	not backward compatible

Note: If you create a sprite file on your computer containing a sprite with no mode number, be careful if you use it with an older Acorn computer running RISC OS 3.10 or earlier, as switching to the brush tool in Paint on RISC OS 3.10 or earlier whilst editing the sprite file will cause Paint to crash.

This sort of file is easy to identify, as at least one of the sprites will fail to show in the sprite file window on those versions of Paint.

You can find out if your sprite file has a such a sprite by displaying the sprite file window using the Full info menu option.