Creating a brush with variable size

When I first started to use GIMP, one of the Photoshop® features I most missed was the ability to resize a brush on-the-fly rather than having to reselect a different size brush or create a new one of the needed size. I searched unsuccessfully for a way to do this.

Recently, as I was looking in the GIMP manual online, I noticed an item 'Creating a brush with variable size'. I hadn't ever noticed this item before, so it's either been recently added or I'm #@%&. At any rate, I'm presenting it here enhanced with screenshots for those of you who would like to make use of this handy feature.

1. Start with opening the Brush dialog by double-clicking on the Brush area in Toolbox, or by File → Dialogs → Brushes. Click on the New Brush button to open the Brush Editor dialog.

   

2. Name your brush at once, 'Variable Round' for instance.
   
   
3. Your brush will appear in the Brush options with a blue corner.
   
4. Now, go File → Preferences → Input Controllers

• Click the Main Mouse Wheel tab.
• Check Enable this controller.
• Scroll through the Events list and select Scroll up (Shift).
• Click on the Edit button to open a window that allows you to assign an action to the selected event.
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5. Click on the small triangle next to Context to drop the list down. Scroll through this list and select the context-brush-radius-increase item.
   
6. Do the same to assign the 'context-brush-radius-decrease' action to the 'Scroll down (Shift)' event to decrease the brush size.
7. Click on the Save button in the Brush Editor to save your brush.

I am using a third-party mouse on my iMac and didn't have success with the scroll wheel actions. However, using the Main Keyboard tab I was able to assign increase and decease brush radius to the up- and down-arrow keys. I also used the left- and right-arrow keys to decrease and increase the hardness of the brush.

If you work with a tool that has a 'Brush' option and have selected your Variable Round brush, press the Shift key and you will be able to vary the brush size by using the mouse wheel or the up- and down-arrow keys. This change will be visible in real time in the brush area of the Toolbox and in the Brush Dialog.

Hope you found this useful. --tab