Bug 769634 - imgITools should provide cropping functionality; r=bbondy

image/public/imgITools.idl

@@ -9,7 +9,7 @@
 interface nsIInputStream;
 interface imgIContainer;
 
-[scriptable, uuid(1f19a2ce-cf5c-4a6b-8ba7-63785b45053f)]
+[scriptable, uuid(8e16f39e-7012-46bd-aa22-2a7a3265608f)]
 interface imgITools : nsISupports
 {
     /**
@@ -60,7 +60,8 @@ interface imgITools : nsISupports
      * @param aMimeType
      *        Type of encoded image desired (eg "image/png").
      * @param aWidth, aHeight
-     *        The size (in pixels) desired for the resulting image.
+     *        The size (in pixels) desired for the resulting image. Specify 0 to
+     *        use the given image's width or height. Values must be >= 0.
      * @param outputOptions
      *        Encoder-specific output options.
      */
@@ -69,4 +70,32 @@ interface imgITools : nsISupports
                                      in long aWidth,
                                      in long aHeight,
                                      [optional] in AString outputOptions);
+
+    /**
+     * encodeCroppedImage
+     * Caller provides an image container, and the mime type it should be
+     * encoded to. We return an input stream for the encoded image data.
+     * The encoded image is cropped to the specified dimensions.
+     *
+     * The given offset and size must not exceed the image bounds.
+     *
+     * @param aContainer
+     *        An image container.
+     * @param aMimeType
+     *        Type of encoded image desired (eg "image/png").
+     * @param aOffsetX, aOffsetY
+     *        The crop offset (in pixels). Values must be >= 0.
+     * @param aWidth, aHeight
+     *        The size (in pixels) desired for the resulting image. Specify 0 to
+     *        use the given image's width or height. Values must be >= 0.
+     * @param outputOptions
+     *        Encoder-specific output options.
+     */
+    nsIInputStream encodeCroppedImage(in imgIContainer aContainer,
+                                      in ACString aMimeType,
+                                      in long aOffsetX,
+                                      in long aOffsetY,
+                                      in long aWidth,
+                                      in long aHeight,
+                                      [optional] in AString outputOptions);
 };

image/src/imgTools.cpp

@@ -102,12 +102,14 @@ NS_IMETHODIMP imgTools::EncodeImage(imgIContainer *aContainer,
                                     const nsAString& aOutputOptions,
                                     nsIInputStream **aStream)
 {
-    return EncodeScaledImage(aContainer,
-                             aMimeType,
-                             0,
-                             0,
-                             aOutputOptions,
-                             aStream);
+  nsresult rv;
+
+  // Use frame 0 from the image container.
+  nsRefPtr<gfxImageSurface> frame;
+  rv = GetFirstImageFrame(aContainer, getter_AddRefs(frame));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return EncodeImageData(frame, aMimeType, aOutputOptions, aStream);
 }
 
 NS_IMETHODIMP imgTools::EncodeScaledImage(imgIContainer *aContainer,
@@ -117,20 +119,111 @@ NS_IMETHODIMP imgTools::EncodeScaledImage(imgIContainer *aContainer,
                                           const nsAString& aOutputOptions,
                                           nsIInputStream **aStream)
 {
-  nsresult rv;
-  bool doScaling = true;
-  PRUint8 *bitmapData;
-  PRUint32 bitmapDataLength, strideSize;
+  NS_ENSURE_ARG(aScaledWidth >= 0 && aScaledHeight >= 0);
 
   // If no scaled size is specified, we'll just encode the image at its
   // original size (no scaling).
   if (aScaledWidth == 0 && aScaledHeight == 0) {
-    doScaling = false;
-  } else {
-    NS_ENSURE_ARG(aScaledWidth > 0);
-    NS_ENSURE_ARG(aScaledHeight > 0);
+    return EncodeImage(aContainer, aMimeType, aOutputOptions, aStream);
   }
 
+  // Use frame 0 from the image container.
+  nsRefPtr<gfxImageSurface> frame;
+  nsresult rv = GetFirstImageFrame(aContainer, getter_AddRefs(frame));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  PRInt32 frameWidth = frame->Width(), frameHeight = frame->Height();
+
+  // If the given width or height is zero we'll replace it with the image's
+  // original dimensions.
+  if (aScaledWidth == 0) {
+    aScaledWidth = frameWidth;
+  } else if (aScaledHeight == 0) {
+    aScaledHeight = frameHeight;
+  }
+
+  // Create a temporary image surface
+  nsRefPtr<gfxImageSurface> dest = new gfxImageSurface(gfxIntSize(aScaledWidth, aScaledHeight),
+                                                       gfxASurface::ImageFormatARGB32);
+  gfxContext ctx(dest);
+
+  // Set scaling
+  gfxFloat sw = (double) aScaledWidth / frameWidth;
+  gfxFloat sh = (double) aScaledHeight / frameHeight;
+  ctx.Scale(sw, sh);
+
+  // Paint a scaled image
+  ctx.SetOperator(gfxContext::OPERATOR_SOURCE);
+  ctx.SetSource(frame);
+  ctx.Paint();
+
+  return EncodeImageData(dest, aMimeType, aOutputOptions, aStream);
+}
+
+NS_IMETHODIMP imgTools::EncodeCroppedImage(imgIContainer *aContainer,
+                                           const nsACString& aMimeType,
+                                           PRInt32 aOffsetX,
+                                           PRInt32 aOffsetY,
+                                           PRInt32 aWidth,
+                                           PRInt32 aHeight,
+                                           const nsAString& aOutputOptions,
+                                           nsIInputStream **aStream)
+{
+  NS_ENSURE_ARG(aOffsetX >= 0 && aOffsetY >= 0 && aWidth >= 0 && aHeight >= 0);
+
+  // Offsets must be zero when no width and height are given or else we're out
+  // of bounds.
+  NS_ENSURE_ARG(aWidth + aHeight > 0 || aOffsetX + aOffsetY == 0);
+
+  // If no size is specified then we'll preserve the image's original dimensions
+  // and don't need to crop.
+  if (aWidth == 0 && aHeight == 0) {
+    return EncodeImage(aContainer, aMimeType, aOutputOptions, aStream);
+  }
+
+  // Use frame 0 from the image container.
+  nsRefPtr<gfxImageSurface> frame;
+  nsresult rv = GetFirstImageFrame(aContainer, getter_AddRefs(frame));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  PRInt32 frameWidth = frame->Width(), frameHeight = frame->Height();
+
+  // If the given width or height is zero we'll replace it with the image's
+  // original dimensions.
+  if (aWidth == 0) {
+    aWidth = frameWidth;
+  } else if (aHeight == 0) {
+    aHeight = frameHeight;
+  }
+
+  // Check that the given crop rectangle is within image bounds.
+  NS_ENSURE_ARG(frameWidth >= aOffsetX + aWidth &&
+                frameHeight >= aOffsetY + aHeight);
+
+  // Create a temporary image surface
+  nsRefPtr<gfxImageSurface> dest = new gfxImageSurface(gfxIntSize(aWidth, aHeight),
+                                                       gfxASurface::ImageFormatARGB32);
+  gfxContext ctx(dest);
+
+  // Set translate
+  ctx.Translate(gfxPoint(-aOffsetX, -aOffsetY));
+
+  // Paint a scaled image
+  ctx.SetOperator(gfxContext::OPERATOR_SOURCE);
+  ctx.SetSource(frame);
+  ctx.Paint();
+
+  return EncodeImageData(dest, aMimeType, aOutputOptions, aStream);
+}
+
+NS_IMETHODIMP imgTools::EncodeImageData(gfxImageSurface *aSurface,
+                                        const nsACString& aMimeType,
+                                        const nsAString& aOutputOptions,
+                                        nsIInputStream **aStream)
+{
+  PRUint8 *bitmapData;
+  PRUint32 bitmapDataLength, strideSize;
+
   // Get an image encoder for the media type
   nsCAutoString encoderCID(
     NS_LITERAL_CSTRING("@mozilla.org/image/encoder;2?type=") + aMimeType);
@@ -139,60 +232,20 @@ NS_IMETHODIMP imgTools::EncodeScaledImage(imgIContainer *aContainer,
   if (!encoder)
     return NS_IMAGELIB_ERROR_NO_ENCODER;
 
-  // Use frame 0 from the image container.
-  nsRefPtr<gfxImageSurface> frame;
-  rv = aContainer->CopyFrame(imgIContainer::FRAME_CURRENT, true,
-                             getter_AddRefs(frame));
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (!frame)
-    return NS_ERROR_NOT_AVAILABLE;
-
-  PRInt32 w = frame->Width(), h = frame->Height();
-  if (!w || !h)
-    return NS_ERROR_FAILURE;
-
-  nsRefPtr<gfxImageSurface> dest;
-
-  if (!doScaling) {
-    // If we're not scaling the image, use the actual width/height.
-    aScaledWidth  = w;
-    aScaledHeight = h;
-
-    bitmapData = frame->Data();
+  bitmapData = aSurface->Data();
   if (!bitmapData)
     return NS_ERROR_FAILURE;
 
-    strideSize = frame->Stride();
-    bitmapDataLength = aScaledHeight * strideSize;
+  strideSize = aSurface->Stride();
 
-  } else {
-    // Prepare to draw a scaled version of the image to a temporary surface...
-
-    // Create a temporary image surface
-    dest = new gfxImageSurface(gfxIntSize(aScaledWidth, aScaledHeight),
-                               gfxASurface::ImageFormatARGB32);
-    gfxContext ctx(dest);
-
-    // Set scaling
-    gfxFloat sw = (double) aScaledWidth / w;
-    gfxFloat sh = (double) aScaledHeight / h;
-    ctx.Scale(sw, sh);
-
-    // Paint a scaled image
-    ctx.SetOperator(gfxContext::OPERATOR_SOURCE);
-    ctx.SetSource(frame);
-    ctx.Paint();
-
-    bitmapData = dest->Data();
-    strideSize = dest->Stride();
-    bitmapDataLength = aScaledHeight * strideSize;
-  }
+  PRInt32 width = aSurface->Width(), height = aSurface->Height();
+  bitmapDataLength = height * strideSize;
 
   // Encode the bitmap
-  rv = encoder->InitFromData(bitmapData,
+  nsresult rv = encoder->InitFromData(bitmapData,
                                       bitmapDataLength,
-                             aScaledWidth,
-                             aScaledHeight,
+                                      width,
+                                      height,
                                       strideSize,
                                       imgIEncoder::INPUT_FORMAT_HOSTARGB,
                                       aOutputOptions);
@@ -201,3 +254,17 @@ NS_IMETHODIMP imgTools::EncodeScaledImage(imgIContainer *aContainer,
 
   return CallQueryInterface(encoder, aStream);
 }
+
+NS_IMETHODIMP imgTools::GetFirstImageFrame(imgIContainer *aContainer,
+                                           gfxImageSurface **aSurface)
+{
+  nsRefPtr<gfxImageSurface> frame;
+  nsresult rv = aContainer->CopyFrame(imgIContainer::FRAME_CURRENT, true,
+                                      getter_AddRefs(frame));
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(frame, NS_ERROR_NOT_AVAILABLE);
+  NS_ENSURE_TRUE(frame->Width() && frame->Height(), NS_ERROR_FAILURE);
+
+  frame.forget(aSurface);
+  return NS_OK;
+}

image/src/imgTools.h

@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "imgITools.h"
+#include "gfxContext.h"
 
 #define NS_IMGTOOLS_CID \
 { /* fd9a9e8a-a77b-496a-b7bb-263df9715149 */         \
@@ -22,4 +23,13 @@ public:
 
   imgTools();
   virtual ~imgTools();
+
+private:
+  NS_IMETHODIMP EncodeImageData(gfxImageSurface *aSurface,
+                                const nsACString& aMimeType,
+                                const nsAString& aOutputOptions,
+                                nsIInputStream **aStream);
+
+  NS_IMETHODIMP GetFirstImageFrame(imgIContainer *aContainer,
+                                   gfxImageSurface **aSurface);
 };

image/test/unit/test_imgtools.js

@@ -431,6 +431,214 @@ referenceBytes = streamToArray(istream);
 compareArrays(encodedBytes, referenceBytes);
 
 
+/* ========== 15 ========== */
+testnum++;
+testdesc = "test cropping a JPG";
+
+// 32x32 jpeg, 3494 bytes.
+imgName = "image2.jpg";
+inMimeType = "image/jpeg";
+imgFile = do_get_file(imgName);
+
+istream = getFileInputStream(imgFile);
+do_check_eq(istream.available(), 3494);
+
+outParam = {};
+imgTools.decodeImageData(istream, inMimeType, outParam);
+container = outParam.value;
+
+// It's not easy to look at the pixel values from JS, so just
+// check the container's size.
+do_check_eq(container.width,  32);
+do_check_eq(container.height, 32);
+
+// encode a cropped image
+istream = imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, 16, 16);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg16x16cropped.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 879);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 16 ========== */
+testnum++;
+testdesc = "test cropping a JPG with an offset";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeCroppedImage(container, "image/jpeg", 16, 16, 16, 16);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg16x16cropped2.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 878);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 17 ========== */
+testnum++;
+testdesc = "test cropping a JPG without a given height";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, 16, 0);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg16x32cropped3.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1127);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 18 ========== */
+testnum++;
+testdesc = "test cropping a JPG without a given width";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, 0, 16);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg32x16cropped4.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1135);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 19 ========== */
+testnum++;
+testdesc = "test cropping a JPG without a given width and height";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, 0, 0);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg32x32.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1634);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 20 ========== */
+testnum++;
+testdesc = "test scaling a JPG without a given width";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeScaledImage(container, "image/jpeg", 0, 16);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg32x16scaled.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1227);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 21 ========== */
+testnum++;
+testdesc = "test scaling a JPG without a given height";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeScaledImage(container, "image/jpeg", 16, 0);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg16x32scaled.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1219);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 22 ========== */
+testnum++;
+testdesc = "test scaling a JPG without a given width and height";
+
+// we'll reuse the container from the previous test
+istream = imgTools.encodeScaledImage(container, "image/jpeg", 0, 0);
+encodedBytes = streamToArray(istream);
+
+// Get bytes for exected result
+refName = "image2jpg32x32.jpg";
+refFile = do_get_file(refName);
+istream = getFileInputStream(refFile);
+do_check_eq(istream.available(), 1634);
+referenceBytes = streamToArray(istream);
+
+// compare the encoder's output to the reference file.
+compareArrays(encodedBytes, referenceBytes);
+
+
+/* ========== 22 ========== */
+testnum++;
+testdesc = "test invalid arguments for cropping";
+
+var numErrors = 0;
+
+try {
+  // width/height can't be negative
+  imgTools.encodeScaledImage(container, "image/jpeg", -1, -1);
+} catch (e) { numErrors++; }
+
+try {
+  // offsets can't be negative
+  imgTools.encodeCroppedImage(container, "image/jpeg", -1, -1, 16, 16);
+} catch (e) { numErrors++; }
+
+try {
+  // width/height can't be negative
+  imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, -1, -1);
+} catch (e) { numErrors++; }
+
+try {
+  // out of bounds
+  imgTools.encodeCroppedImage(container, "image/jpeg", 17, 17, 16, 16);
+} catch (e) { numErrors++; }
+
+try {
+  // out of bounds
+  imgTools.encodeCroppedImage(container, "image/jpeg", 0, 0, 33, 33);
+} catch (e) { numErrors++; }
+
+try {
+  // out of bounds
+  imgTools.encodeCroppedImage(container, "image/jpeg", 1, 1, 0, 0);
+} catch (e) { numErrors++; }
+
+do_check_eq(numErrors, 6);
+
+
 /* ========== bug 363986 ========== */
 testnum = 363986;
 testdesc = "test PNG and JPEG encoders' Read/ReadSegments methods";