Step 3: Color Detection

Pick colors from anywhere on the screen.

Where We Are

You have a popover with placeholder content. Now we make it actually detect colors.

Add Color Picking

This is the core functionality:

When the popover opens, detect the color under the cursor and display it.
- Update the color preview square with the actual color
- Show the real hex value
- Show the real RGB values
- Show the real HSL values

The color should update when the popover opens.

Let Claude implement this. It will likely need to:

• Request screen recording permission (macOS security requirement)
• Use macOS APIs to sample screen color
• Convert between color formats

Handle Permissions

macOS requires permission to read screen colors. When you first run:

1. You'll likely see a permission prompt
2. Grant "Screen Recording" permission in System Settings
3. You may need to restart the app

If Claude's implementation doesn't handle permissions smoothly:

Add proper permission handling for screen capture.
If we don't have permission, show a message explaining what to do.

Test It

1. Move your cursor over something colorful
2. Click the menu bar icon
3. The popover should show that color

Try different colors:

• A blue icon
• White background
• Your desktop picture

Does it detect the correct color?

Common Issues

Wrong color / always white

The color detection is showing the wrong color.
It seems to be picking up [what it shows] instead of what's under the cursor.

Permission denied

I'm getting a permission error when trying to capture screen color.
How do I request the right permissions?

App doesn't update

The color doesn't update when I open the popover over different colors.
It stays the same every time.

Refine the Display

Once color picking works, refine how values are displayed:

Format the values nicely:
- Hex should be uppercase with a # symbol (#FF5733)
- RGB should be formatted as "RGB(255, 87, 51)"
- HSL should be formatted as "HSL(14°, 100%, 60%)"

Checkpoint

By now you should have:

• Color detection working
• Real colors showing in the preview
• Hex, RGB, HSL values displaying correctly
• Proper formatting

Stuck?

Color detection is the trickiest part. If it's not working:

1. Check permissions first — System Settings → Privacy & Security → Screen Recording. Your app needs to be listed and enabled.
2. Restart the app — Permission changes often require a restart
3. Compare to reference — Look at reference/ColorDrop/Sources/ColorDrop/ColorManager.swift for a working implementation
4. Ask Claude to debug — "Color detection isn't working. Here's my ColorManager code: [paste]. What might be wrong?"

See Getting Unstuck for more debugging strategies.

What You Learned

• How to work with system permissions
• Claude can handle complex APIs (screen capture, color conversion)
• Describing the format you want for data display

Exercises

1. Run the "Add Color Picking" prompt, then grant Screen Recording permission and restart the app so detection actually works.
2. Test detection over at least three surfaces (a colored icon, a white background, your desktop picture) and confirm each reads correctly.
3. Apply the "Refine the Display" prompt and verify the hex is uppercase with #, RGB reads RGB(255, 87, 51), and HSL reads HSL(14°, 100%, 60%).