9. Varying brush size

9. Varying brush size
	第 7 章 Painting with GIMP

From GIMP-2.4, all brushes have a variable size.

9.1. How to vary the height of a brush

You can get the brush size varying in three ways:

Using the Scale slider of the tool that uses the brush. Pencil, Paintbrush, Eraser, Airbrush, Clone, Heal, Perspective Clone, Blur/Sharpen and Dodge/Burn tools have a slider to vary brush size.

图 7.20. The Scale slider
By programming the mouse wheel:
1. In the main window of GIMP, click on Edit → Preferences.
2. In the left column of the new window, select Input Devices → Input Controllers.
3. You can see Additional Input Controllers, with two columns: Available Controllers and Active Controllers.
  
  In the column Active Controllers, double-click the Main Mouse Wheel button.
4. Then, you see a new window: Configure Input Controller.
  
  In the left column Event, click Scroll Up to get it highlighted.
5. Click the Edit button (at the bottom middle of the list).
6. You can see the window Select Controller Event Action.
  
  Drop-down the Tools item, by clicking the small triangle on its left.
7. In the left column Action, click Increase Brush Scale to highlight it, then click the OK button.
8. Now, in front of Scroll Up is display tools-paint-brush-scale-increase.
9. Close the window.
10. With the same method, program Scroll Down with Decrease Brush Scale.
11. Don't forget to click the OK button of the main window of Preferences.
After these somewhat long explanations, you can use your mouse wheel to vary size brush. For example, choose the pencil tool with the “Circle” brush. Set the pointer in the image window, use the mouse wheel, in the two directions, you can see the “Circle” shrinking or stretching.
You can program the “Up” and “Down” arrow keys of the keyboard.

The method is similar to that of the mouse wheel. The only differences are:
- In the column Active Controllers, double-click Main Keyboard.
- In the column Event, click Cursor Up for the first key, and Cursor Down for the second key.
- Then, use the two keys (Up arrow and Down arrow) and the result is the same as you got with the mouse wheel.