RISC OS 3.7 User Guide

19 Paint

You'll probably find that the easiest way of learning Paint is to read through Basic ideas (on the next page) and then work through the Paint tutorial which follows, before coming back to the Paint reference section starting on page 297.

Starting Paint

1 Double-click on the !Paint icon to install it on the icon bar.

2 Click on the Paint icon bar icon to display the Create new sprite window.

3 Fill in the details for your new sprite and click on OK (it's probably best to follow the tutorial starting on page 285 if you don't already know how to do this).

Basic ideas

A sprite is a graphic shape made up of an arrangement of pixels (the smallest unit the screen uses in its current mode). Sprites are stored in sprite files, which can contain more than one sprite. Sprites and sprite files use a standard format, so you can freely export images produced by Paint to other RISC OS applications (such as Draw) that recognise sprites. You can also use Paint to edit sprites produced by other RISC OS applications, and to import and edit JPEG files.

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

• 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 - see page 287).

• 32-thousand and 16-million colour sprites make use of the Colours window described in Using colour in applications on page 179.

Creating sprite files compatible with earlier versions of RISC OS

Paint reference section

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 (see page 299).

• 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

1 Click on the Paint icon on the icon bar.

2 Define the sprite's attributes in the Create new sprite window:

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[1]. The default is the size of the current display.

  You can also click on the resize arrows at the bottom of the window.

  

• 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

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[2]. You can save it under a different name, if you want.
• 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

To:

• Open a sprite for editing: Double-click on its picture in the Sprite file window. See page 306 and page 311 for more on editing sprites. 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

• 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

The image will be converted into a sprite in the current screen mode. This means that it will be given the same number of colours as the current mode, so make sure you change to the correct mode before you load the image.

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 Output options on page 346.

• 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

There are in fact two different Colours windows (see Using colour in applications on page 179 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 (see Mixing new colours using a palette on page 304).

Finding out the colour of an individual pixel

Making the Colours window smaller

Using a transparent mask

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

For more information about using masks, see page 295.

Applying colours using logical operators

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.

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

Giving a sprite a palette

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)

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

Saving a palette

1 Click Menu over the sprite window and display the Save/Palette box:

2 Drag the Save as icon to a directory display.

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)

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

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

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

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.

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 on page 309.

• 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:

  Lines. 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

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

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

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

• 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.

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 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 Configuring applications on page 427.

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

• 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.

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.