Fix icon sizing bug (2x resolution issue)

CHANGELOG.md

@@ -7,7 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-### Added
+### Fixed
+- Fixed icon sizing bug where output images were created at 2× the requested dimensions (e.g., 512px request would produce 1024px output) ([#3](https://github.com/macadmins/icongrabber/issues/3))
+- Corrected bitmap creation to use explicit pixel dimensions instead of relying on NSImage.size which was affected by Retina scaling
+
+### Changed
+- Improved test suite with pixel dimension verification using `sips` to ensure icons are created at exact requested sizes
+- Added 4 new dimension verification tests covering standard icon sizes (64×64, 256×256, 512×512, 1024×1024)
 
 ---
 

icongrabber-cli/main.swift

@@ -234,36 +234,46 @@ func extractIcon(from appPath: String, size: Int) throws -> NSImage {
     // Get the icon for the application
     let icon = NSWorkspace.shared.icon(forFile: url.path)
 
-    // Set the size
-    let iconSize = NSSize(width: size, height: size)
-    icon.size = iconSize
-
     return icon
 }
 
 func saveIconAsPNG(_ icon: NSImage, to outputPath: String, size: Int) throws {
     let url = URL(fileURLWithPath: outputPath)
     let iconSize = NSSize(width: size, height: size)
 
-    // Create a bitmap representation
-    guard let tiffData = icon.tiffRepresentation,
-          let _ = NSBitmapImageRep(data: tiffData) else {
+    // Create a bitmap representation with exact pixel dimensions
+    guard let bitmapRep = NSBitmapImageRep(
+        bitmapDataPlanes: nil,
+        pixelsWide: size,
+        pixelsHigh: size,
+        bitsPerSample: 8,
+        samplesPerPixel: 4,
+        hasAlpha: true,
+        isPlanar: false,
+        colorSpaceName: .deviceRGB,
+        bytesPerRow: 0,
+        bitsPerPixel: 0
+    ) else {
         throw CLIError.exportFailed("Could not create bitmap representation")
     }
 
-    // Resize to exact dimensions
-    let resizedImage = NSImage(size: iconSize)
-    resizedImage.lockFocus()
+    // Draw the icon into the bitmap context at exact pixel dimensions
+    NSGraphicsContext.saveGraphicsState()
+    guard let context = NSGraphicsContext(bitmapImageRep: bitmapRep) else {
+        throw CLIError.exportFailed("Could not create graphics context")
+    }
+    NSGraphicsContext.current = context
+
+    // Draw icon scaled to exact size
     icon.draw(in: NSRect(origin: .zero, size: iconSize),
-             from: NSRect(origin: .zero, size: icon.size),
+             from: NSRect.zero,
              operation: .copy,
              fraction: 1.0)
-    resizedImage.unlockFocus()
+
+    NSGraphicsContext.restoreGraphicsState()
 
     // Convert to PNG
-    guard let resizedTiff = resizedImage.tiffRepresentation,
-          let resizedBitmap = NSBitmapImageRep(data: resizedTiff),
-          let pngData = resizedBitmap.representation(using: .png, properties: [:]) else {
+    guard let pngData = bitmapRep.representation(using: .png, properties: [:]) else {
         throw CLIError.exportFailed("Could not create PNG data")
     }
 

tests/run_tests.sh

@@ -80,6 +80,25 @@ assert_exit_code() {
     fi
 }
 
+assert_image_dimensions() {
+    local file=$1
+    local expected_width=$2
+    local expected_height=$3
+    if [ -f "$file" ]; then
+        # Use sips to get actual pixel dimensions
+        local width=$(sips -g pixelWidth "$file" 2>/dev/null | grep pixelWidth | awk '{print $2}')
+        local height=$(sips -g pixelHeight "$file" 2>/dev/null | grep pixelHeight | awk '{print $2}')
+
+        if [ "$width" = "$expected_width" ] && [ "$height" = "$expected_height" ]; then
+            pass_test
+        else
+            fail_test "Expected ${expected_width}x${expected_height}, got ${width}x${height}"
+        fi
+    else
+        fail_test "File $file does not exist"
+    fi
+}
+
 assert_file_size_under() {
     local file=$1
     local max_kb=$2
@@ -145,16 +164,28 @@ print_test 2 "Custom size extraction (256x256)"
 $CLI "$TEST_APP" -s 256 -o test_256.png -f
 assert_file_exists "test_256.png"
 
+# Test 2a: Verify 256x256 dimensions
+print_test "2a" "Verify 256x256 pixel dimensions"
+assert_image_dimensions "test_256.png" 256 256
+
 # Test 3: Small size (64x64)
 print_test 3 "Small icon extraction (64x64)"
 $CLI "$TEST_APP" -s 64 -o test_64.png -f
 assert_file_exists "test_64.png"
 
+# Test 3a: Verify 64x64 dimensions
+print_test "3a" "Verify 64x64 pixel dimensions"
+assert_image_dimensions "test_64.png" 64 64
+
 # Test 4: Large size (1024x1024)
 print_test 4 "Large icon extraction (1024x1024)"
 $CLI "$TEST_APP" -s 1024 -o test_1024.png -f
 assert_file_exists "test_1024.png"
 
+# Test 4a: Verify 1024x1024 dimensions
+print_test "4a" "Verify 1024x1024 pixel dimensions"
+assert_image_dimensions "test_1024.png" 1024 1024
+
 # Test 5: File size validation (should be reasonable)
 print_test 5 "Output file size validation"
 assert_file_size "test_basic.png" 1000
@@ -232,6 +263,22 @@ else
     fail_test "Some size extractions failed"
 fi
 
+# Test 13a: Verify all standard size dimensions are correct
+print_test "13a" "Verify all standard sizes have correct dimensions"
+all_correct=true
+for size in "${sizes[@]}"; do
+    width=$(sips -g pixelWidth "test_${size}.png" 2>/dev/null | grep pixelWidth | awk '{print $2}')
+    height=$(sips -g pixelHeight "test_${size}.png" 2>/dev/null | grep pixelHeight | awk '{print $2}')
+    if [ "$width" != "$size" ] || [ "$height" != "$size" ]; then
+        fail_test "Size ${size}: Expected ${size}x${size}, got ${width}x${height}"
+        all_correct=false
+        break
+    fi
+done
+if [ "$all_correct" = true ]; then
+    pass_test
+fi
+
 # Test 14: Force flag to overwrite without prompt
 print_test 14 "Force flag overwrites without prompting"
 $CLI "$TEST_APP" -o test_overwrite.png -s 128