# HUIYA 0.21.1 — User Guide

HUIYA is a portable Windows digital painting app. Run `HUIYA.exe`; no separate .NET installation is required.

## Requirements

- Windows 10 / 11 (64-bit)
- A Direct2D-capable graphics device
- A pen tablet or touch screen for pressure input
- About 100 MB of free disk space

## First launch

- A 7-day trial starts on first launch. The trial status is shown in the top-right corner; click it to open the activation window.
- Activation is offline: copy the machine code, send it to the software provider, then paste the activation code and click Activate.
- After the trial ends, editing is blocked, but saving, Save As and image export still work.
- Changing the system clock may trigger a time warning. Restore the correct time and restart the app.
- Reinstalling Windows or changing the computer may change the machine code, so a new activation code may be required.

## Workspace

- Left: toolbox and the current tool's properties.
- Center: the canvas. The bar above the canvas shows the document name, save state, current tool, edit target and selection status.
- Right: Color / Palette tabs and Layers / Properties & Masks tabs.
- Drag the splitters to resize panels. Press Tab to hide or restore the side panels. View > Reset Layout restores the default layout.
- The top menus provide File, Edit and View commands, plus undo and redo.

## Tools and shortcuts

| Tool or action | Shortcut |
| --- | --- |
| Brush | B |
| Blend | M |
| Watercolor | W |
| Texture | T |
| Smudge (drag color) | U |
| Blur | L |
| Eraser | E |
| Eyedropper | I |
| Fill | F |
| Gradient | G |
| Transform | Ctrl+T |
| Move | V |
| Quick Mask | Q |
| Undo | Ctrl+Z |
| Redo | Ctrl+Y or Ctrl+Shift+Z |
| Select all | Ctrl+A |
| Deselect | Ctrl+D |
| Invert selection | Ctrl+I |
| Open | Ctrl+O |
| Save | Ctrl+S |
| Save As | Ctrl+Shift+S |
| Swap foreground/background | X |
| Default colors | D |
| Brush size | [ and ] |
| Pan | Space + drag |
| Zoom | Mouse wheel |
| Rotate canvas | Shift + mouse wheel |
| Cancel gesture, stroke or transform | Esc |

Rectangular selection, Lasso, Magic Wand and Liquify are available directly from the left toolbox. Mesh Warp is a mode of the Transform tool.

## Brushes and paint

- Brush paints with the foreground color. Blend mixes existing colors; increasing Color Rate adds the foreground color.
- Watercolor lays down soft color and mixes the layer beneath the stroke. Texture adds paper fiber, woven cloth or grain.
- Smudge drags existing color along the stroke. Blur softens color boundaries and stroke edges without adding paint.
- Brush controls include size, hardness, spacing, smoothing and pressure curves. The eraser remembers its own size.
- Click a color swatch, a palette entry, or enter a six-digit hex color and press Enter.
- Smudge settings include smudge strength, Color Rate, sampling radius and Smear Alpha. Color Rate 0 is pure mixing. The sampling radius applies to Blend, not Smudge.
- Texture strength 0 produces a plain brush. Textures are fixed to canvas coordinates and do not jump between strokes.

## Layers, masks and blending

- A document supports up to 32 layers. Raw layer data is limited to 256 MiB, and undo history to 50 steps or 512 MiB.
- Use the plus button to add a layer. The eye icon toggles visibility. Layer thumbnails, names and opacity are in the layer list. Use the bottom buttons to move up, move down, clear or delete.
- Blend modes: Normal, Multiply, Screen, Overlay, Color and Add / Linear Dodge.
- Layer mask: add a mask, then click the mask thumbnail to edit it. Black hides, white shows. Press X to swap foreground and background, or D to reset black/white. Mask painting uses the normal brush engine, including pressure, texture and wet tools.
- The highlighted thumbnail border shows the current edit target. Click the image thumbnail to return to image editing.
- Mask commands include enable/disable, hide all, invert, delete, create from selection and mask to selection.
- Clipping mask: enable "Clip to layer below" on an upper layer. It uses the nearest unclipped base layer's alpha, enabled mask and opacity. Hiding the base layer also hides its clipped layers.
- Quick Mask (Q): paint the selection as grayscale. Black adds to the protected red area; X switches to white to add it back. The red overlay is an editing hint only. Exit Quick Mask to return to painting.
- Selections are shown as a black/white dashed outline. Soft grayscale values still affect painting. An empty selection blocks painting; press Ctrl+D to clear it.
- Rectangular selection: drag on the canvas. Hold Shift to add or Alt to subtract. Lasso closes automatically when you release. Magic Wand supports tolerance, contiguous/all matching areas and sampling all visible layers.
- Selections limit Brush, wet tools, Liquify, Fill, Clear and layer-mask painting. Wet tools may still sample colors outside the selection.

## Transform, Liquify and Mesh Warp

- Transform (Ctrl+T) works around the current layer content or the active selection without opening a dialog. Modes include Move, Scale (Shift keeps proportions), Rotate (Shift snaps to 15 degrees), Perspective, Flip Horizontal/Vertical, 90-degree rotation and Mesh Warp.
- Click outside the canvas, switch tools, save, or press Enter to apply a transform. Esc cancels. One document undo reverts the whole transform.
- Liquify works directly on the main canvas. Modes: Push, Bloat, Pinch, Push Left, Push Right, Clockwise and Counterclockwise. Hold Alt to reverse the direction. Adjust strength, hardness, antialiasing and optional pen pressure. One undo reverts one stroke.
- Mesh Warp starts at 3 x 3. Columns and rows can be set from 1 to 20. Drag a range to choose the area, or Ctrl+drag to choose a new range. Drag grid nodes or cell interiors to deform. The result is applied by clicking outside the canvas, switching tools, saving or pressing Enter; Esc cancels.
- Mesh Warp uses its own rectangular range and does not use the grayscale selection. Liquify and Mesh Warp cannot edit a layer mask directly; return to image editing first.

## Color adjustments

- Hue / Saturation / Lightness, Brightness / Contrast, Levels, Curves and Color Balance are available from the Color Adjustments menu.
- Adjustments apply to the current image layer's pixels. An active selection limits the effect by its grayscale values. Alpha is preserved.
- The preview is temporary. Apply commits one undo step; Cancel or Esc leaves the image unchanged.
- HUIYA uses direct pixel adjustments, not adjustment layers. The image pipeline is 8-bit BGRA without additional ICC or high-bit-depth color management.

## Files and recovery

- File > New Canvas creates a canvas from 1 to 4096 pixels, in square, landscape or portrait orientation.
- Ctrl+O opens a `.drawproject` file or a PNG, JPEG or BMP image.
- Ctrl+S saves a `.drawproject` with all layers, names, order, opacity and visibility. Ctrl+Shift+S saves a copy.
- PNG export composites all visible layers and keeps transparency. PNG does not preserve layers, so save the project if you want to keep editing.
- A recovery copy is written every minute. It is stored in `%LOCALAPPDATA%\DrawingApp`. Recovery does not replace manual saving.
- The custom palette is stored in `%LOCALAPPDATA%\Huiya\palette.json` (up to 64 colors).
- The language preference is stored in `%LOCALAPPDATA%\Huiya\language.txt`. English, Simplified Chinese and Japanese are available.
- The project format is version 3. HUIYA can open version 1 and 2 projects; older app versions cannot open version 3.

## Performance notes

- Wet tools, masks, normal brushes, Liquify and Mesh Warp run on background workers. The UI uploads completed 64-pixel tiles.
- Very fast input can outpace computation. Lifting the pen or saving waits for pending work to finish.
- Large canvases and large brushes may still take time. Frame rate is not guaranteed on every device.

## Troubleshooting

- **SmartScreen warning:** choose More info, then Run anyway.
- **Time warning:** restore the correct system time and restart the app.
- **Activation:** the machine code may change after reinstalling Windows or changing hardware.
- **Trial expired:** editing is blocked, but saving and exporting still work. Activate to resume editing.

## License

HUIYA is proprietary software for personal use, provided without warranty. Do not decompile, modify or redistribute it without permission. Trial and offline activation are handled inside the app; this website does not collect accounts, payments or license data.