Documents and Modes
What a document is drawn for, how big it can be, and what its file holds.
Machines and modes
Each part of a document is drawn for one mode of one machine, chosen when the part is made. The New Document sheet’s Target names the machine and Mode lists the modes it displays.
| Target | Modes |
|---|---|
| ZX Spectrum | ULA |
| Timex | ULA, Hi-Colour, Hi-Res |
| ZX Spectrum Next | ULA, Hi-Colour, Hi-Res, Layer 2 256 colours, Layer 2 16 colours, LoRes 256 colours, LoRes 16 colours, 4-bit sprites, 8-bit sprites, 4-bit tiles |
A mode fixes how a pixel’s colour is stored, and so what drawing can do:
- Attribute modes, ULA and Hi-Colour, store one bit per pixel and an INK, PAPER, BRIGHT and FLASH for each cell: 8 × 8 pixels in ULA, 8 × 1 in Hi-Colour.
- Hi-Res stores one bit per pixel in one ink colour and its complement for the whole screen.
- Palette modes, Layer 2 and LoRes, store a palette index per pixel.
- Pattern modes, sprites and tiles, store a palette index per pixel in patterns of 16 × 16 or 8 × 8, with a transparent value. The 4-bit modes also store a palette bank for each pattern.
Every mode’s size, colours, cells and transparency are listed on Target Modes.
Canvas size
A canvas is any size from one step to 4096 pixels in each direction, in whole steps of the mode’s cell or pattern. The New Document sheet starts the size at the mode’s full screen.
| Mode | Step |
|---|---|
| ULA | 8 × 8 |
| Hi-Colour | 8 × 1 |
| 8-bit and 4-bit sprites | 16 × 16 |
| 4-bit tiles | 8 × 8 |
| every other mode | 1 × 1 |
If a 4-bit sprite document is made 32 × 16, it holds two patterns side by side.
An asset’s size can be changed after the document is made; see Assets.
ULA+
ULA+ replaces the Spectrum’s fixed colours with 64 palette registers, four groups of 8 INK and 8 PAPER colours. The attribute’s BRIGHT and FLASH bits choose the group.
The New Document sheet’s Palette offers ULA+ (64 colours) in ULA and Hi-Colour when the target is ZX Spectrum or ZX Spectrum Next. The Timex target does not offer it.
Half-width pixels
Layer 2 16 colours and Hi-Res store 640 and 512 pixels across a screen 320 and 256 pixels wide, so each pixel is half as wide as it is tall. Block’Ed draws them at that shape.
View ▸ Half-Width Pixels shows Layer 2 16 colours with square pixels instead, and the document keeps the choice. Hi-Res pixels are always half width.
Document files
A Block’Ed document is a project with the extension .blked: a zip archive holding each part as a Block’Ed PNG. Projects and parts are described on Projects.
A Block’Ed PNG shows its artwork in any program that reads PNG. It also holds what a PNG cannot:
- the palette, or the ULA+ registers
- attribute cells, banks and the transparent value
- every asset, frame, frame delay and loop mode
- the painting options: painting mode, colour ramps, perspective, drawing helpers, and whether the frame bar and asset list are showing
Both formats are specified on File Formats.
Block’Ed opens a PNG it wrote, as a project of one part. A PNG from another program is brought in with Import Image…; see Importing Images.
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