The locking and unlocking controls some optimization of the image.. like the DIB. r=kmmclusk sr=buster

gfx/src/windows/nsImageWin.cpp

@@ -62,6 +62,8 @@ nsImageWin :: nsImageWin()
 
   mNaturalWidth = 0;
   mNaturalHeight = 0;
+  mIsLocked = PR_FALSE;
+  mDIBTemp = PR_FALSE;
 
 	//CleanUp(PR_TRUE);
   CleanUpDDB();
@@ -1194,30 +1196,40 @@ PRInt16 numPaletteColors;
 NS_IMETHODIMP
 nsImageWin::LockImagePixels(PRBool aMaskPixels)
 {
-    /*
-  if (!mHBitmap)
-    return NS_ERROR_NOT_INITIALIZED;
+  /*  if (!mHBitmap) return NS_ERROR_NOT_INITIALIZED;
+   ... and do Windows locking of image pixels here, if necessary */
+
+  mIsLocked = PR_TRUE;
 
-   ... and do Windows locking of image pixels here, if necessary
-*/
 	return NS_OK;
 }
 
 /** ---------------------------------------------------
- *	Unlock the pixels
+ *	Unlock the pixels, optimize this nsImageWin
  */
 NS_IMETHODIMP
 nsImageWin::UnlockImagePixels(PRBool aMaskPixels)
 {
-    /*
-  if (!mHBitmap)
+  mIsLocked = PR_FALSE;
+  // if memory was allocated temporarily by GetBits, it can now be deleted safely
+  if (mDIBTemp == PR_TRUE) {
+    // get rid of this memory
+    if (mImageBits != nsnull) {
+      delete [] mImageBits;
+      mImageBits = nsnull;
+      }
+
+    mDIBTemp = PR_FALSE;
+  }
+
+  /* if (!mHBitmap)
     return NS_ERROR_NOT_INITIALIZED;
   
   if (aMaskPixels && !mAlphamHBitmap)
   	return NS_ERROR_NOT_INITIALIZED;
 
-   ... and do Windows unlocking of image pixels here, if necessary
-    */
+   ... and do Windows unlocking of image pixels here, if necessary */
+
 	return NS_OK;
 }
 /** ---------------------------------------------------
@@ -1268,7 +1280,8 @@ nsRect  destRect;
 
 /**
  * Get a pointer to the bits for the pixelmap. Will convert to DIB if
- * only stored in optimized HBITMAP form.
+ * only stored in optimized HBITMAP form.  Using this routine will
+ * set the mDIBTemp flag to true so the next unlock will destroy this memory
  *
  * @return address of the DIB pixel array
  */
@@ -1276,8 +1289,11 @@ nsRect  destRect;
 PRUint8*
 nsImageWin::GetBits()
 {
-  if ( !mImageBits )
+  // if mImageBits did not exist.. then
+  if ( !mImageBits ) {
     ConvertDDBtoDIB(GetWidth(), GetHeight());
+    mDIBTemp = PR_TRUE;   // only set to true if the DIB is being created here as temporary
+  }
 
   return mImageBits;
 

gfx/src/windows/nsImageWin.h

@@ -250,6 +250,8 @@ private:
   PRInt32             mDecodedY1;			    // has been decoded.
   PRInt32             mDecodedX2; 
   PRInt32             mDecodedY2; 
+  PRBool              mIsLocked;			    // variable to keep track of the locking
+  PRBool              mDIBTemp;           // boolean to let us know if DIB was created as temp
 
   PRInt32		          mNaturalWidth;
   PRInt32		          mNaturalHeight;
@@ -260,7 +262,6 @@ private:
   PRInt16             mARowBytes;         // number of bytes per row in the image for tha alpha
   PRInt16             mAlphaWidth;        // alpha layer width
   PRInt16             mAlphaHeight;       // alpha layer height
-  //nsPoint             mLocation;          // alpha mask location
   PRInt8              mImageCache;        // place to save off the old image for fast animation
   PRInt16             mAlphaLevel;        // an alpha level every pixel uses
   HBITMAP             mHBitmap;           // the GDI bitmaps