delta xy is a FREE mouse coordinate measurement program. It allows you to make precise measurements of just about anything on your computer's monitors. It can also show you the ASCII character and key codes for most of the keys on your keyboard, and the RGB value of any pixel on your monitor.
Click on the padlock icon in the upper-right corner of delta xy's window to toggle it open or closed. When it's open, you can switch to other applications. When it's closed, delta xy is “locked” in the foreground. This allows you to click anywhere on your screen to take the necessary measurements, and you'll never switch to another application. You can also toggle the locked/unlocked mode with the Lock command in the File menu, or by pressing command-space.
The top row of numbers (labeled “xy”) indicates the absolute mouse coordinates; where 0,0 is the top-left corner of your main monitor. The second row of numbers (labeled “Δxy”) indicates the mouse coordinates relative to the last place you clicked the mouse.
When delta xy is locked in the foreground, clicking and releasing the mouse anywhere on your screen resets the Δxy values to 1,1. You can also reset Δxy to 1,1 at any time by simultaneously pressing the option and command keys. This works whether delta xy is in the foreground or background, locked or unlocked.
Clicking and dragging the mouse draws a box on screen. The box's coordinates appear in the menu bar next to the Edit menu, and are relative to the last place Δxy was reset to 1,1. While the mouse button is down, the Δxy values correspond to the width and height of the box. The box's coordinates are automatically copied to the clipboard when the mouse button is released. These features only work in locked mode.
Normally, the box coordinates are shown as (left, top, right, bottom). Checking the “QD Rects (t,l,b,r)” item in the File menu shows the box coordinates in standard QuickDraw Rect format (top, left, bottom, right). In either case, you can temporarily toggle to the opposite format by holding down the option key as you drag the box on screen. This feature also only works when delta xy is locked in the foreground.
NOTE: When delta xy is in locked mode, no background applications get any time to run. To safeguard against leaving delta xy locked indefinitely, it automatically unlocks itself after 30 seconds of inactivity (i.e. no mouse movement, mouse clicks, or key presses have occurred). You can override the auto-unlock feature by holding down the option key while you click the padlock closed.
The “char”, “code”, and “key” values in delta xy's window show you the corresponding character, character code (ASCII), and key code for most key combinations you can type on your keyboard. This feature works whether delta xy is in locked or unlocked mode. You can also paste any character from the clipboard to see the character and character code for that character.
The “rgb” value shows you the red, green, and blue color components of any pixel on your monitor. Simply position the cursor directly over the pixel of interest. By default, the color components are displayed as 16-bit values. To view them as 8-bit values, select the “8-Bit RGB Values” item in the File menu. A small color swatch to the right of the RGB values shows the current pixel color. These feature works whether delta xy is in the foreground or background, locked or unlocked.
If the “Bring To Front” menu item is checked, delta xy will attempt make itself the foreground application whenever the option and command keys are pressed simultaneously. It may not always be possible, for instance if the current application is showing a modal dialog. However, the Δxy values will still be reset to 1,1.
Finally, you can copy the xy, Δxy, char/code/key, and rgb values to the clipboard by using the corresponding Copy commands in the Edit menu. Values can be viewed and copied in either decimal or hexadecimal, and delta xy now remembers and restores it's last window position each time you use it.
