Ruler Tool
The Ruler tool helps you position items and measure the distance from one point to another. However, it's not a tool that I would use in image editing, which is what this site concentrates on.
Ruler Tool Options
Sample Size - Select the size of the area the tool will select colour from
Clear All - Clear all the sample points
Tool Presets
You can create and save a Tool Preset for any tool, which will remember settings that you choose for that tool, so you can quickly and easily select different presets and settings for a particular tool. The degree of usefulness of presets varies, depending on the tool.
You can reset any tool back to its default settings by right clicking on the Tool Presets button and select Reset Tool. Take care not to Reset All Tools, unless that is intended.
Measurements
X and Y are co-ordinates for position.
W and H are width and height.
A is angle.
L is length.
Use Measurement Scale
You can set a measurement scale to specify a number of pixels in the image equal to a number of scale units, such as inches, millimeters.
Straighten Layer
Click and drag to draw a line, horizontally or vertically on a part of the image that should be level, such as the surface of water, or the side of a building. Then click the Straighten Layer button to straighten the image.
Although that works great, I usually straighten my images while cropping. When cropping you will see gridlines on the image and it's easy to align these with a horizontal or vertical line. Click and drag just outside the image to rotate the crop.
Clear
This will clear the ruler from the image.
How to use the Ruler Tool
1
Click and drag between two points that you want to measure.
2
Measurements are shown on the Options Bar. Width is shown at 1566 pixels, angle is zero.
3
Measurements are also shown in the Info panel, which is available from the Window menu.
Summary of Ruler Tool
The Ruler tool is not commonly used in image editing, but can be useful when you have need of measuring areas in an image.
