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Make masks and alpha work for wxCOPY when blitting a selected bitmap from a

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wxMemoryDC with an eye towards possibly doing more in the future.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47838 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
David Elliott
2007-08-01 04:14:12 +00:00
parent f87da781d2
commit 50918c652c
1 changed files with 52 additions and 2 deletions
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54
src/cocoa/dcmemory.mm
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@@ -78,6 +78,12 @@ void wxMemoryDC::DoSelect( const wxBitmap& bitmap )
{
CocoaTakeFocus();
wxASSERT(m_cocoaNSImage);
// Replace the bitmap's native data with a newly created one based on the
// NSImage that has been (potentially) drawn upon. Note that this may and
// probably will in many cases change the bitmap's format.
// There is nothing we can do about this using pure Cocoa code. Even using
// CGBitmapContext is not an option because it only supports a limited
// number of bitmap formats. Specifically, 24-bpp is not supported.
m_selectedBitmap.SetNSBitmapImageRep(
[[NSBitmapImageRep alloc]
initWithFocusedViewRect:NSMakeRect(0.0,0.0,
@@ -96,6 +102,16 @@ void wxMemoryDC::DoSelect( const wxBitmap& bitmap )
m_selectedBitmap.GetHeight())];
// Now copy the data
// Pass false to GetNSImage so the mask is not applied as an alpha channel.
// Cocoa uses premultiplied alpha so applying the mask would cause all
// color information masked out to be turned black which is undesirable.
// FIXME: Currently, the mask will not be updated if any drawing occurs.
// My only suggestion is for wxCocoa users to eschew the mask in favor
// of an alpha channel or to recreate the mask after drawing.
// The only way to fix this is to draw twice, once as normal and again
// onto the mask to update it. That would require overriding every
// single drawing primitive (e.g. DoDrawLine, DoDrawRectangle, etc.)
// and would be a major undertaking.
NSImage *nsimage = [m_selectedBitmap.GetNSImage(false) retain];
[m_cocoaNSImage lockFocus];
[nsimage drawAtPoint: NSMakePoint(0,0)
@@ -142,14 +158,48 @@ bool wxMemoryDC::CocoaDoBlitOnFocusedDC(wxCoord xdest, wxCoord ydest,
[transform concat];
[flipTransform concat];
NSImage *sourceImage;
if(useMask)
{
sourceImage = [m_cocoaNSImage copy];
// Apply the mask to the copied image
NSBitmapImageRep *maskRep = m_selectedBitmap.GetMask()->GetNSBitmapImageRep();
NSImage *maskImage = [[NSImage alloc] initWithSize:[maskRep size]];
[maskImage addRepresentation:maskRep];
[sourceImage lockFocus];
[maskImage compositeToPoint:NSZeroPoint operation:NSCompositeDestinationIn];
[sourceImage unlockFocus];
[maskImage release];
}
else
{ // retain the m_cocoaNSImage so it has the same ownership as the copy done in the other case.
sourceImage = [m_cocoaNSImage retain];
}
NSCompositingOperation drawingOp;
switch(logicalFunc)
{
case wxCOPY:
// Even if not using the mask, the image might have an alpha channel
// so always use NSCompositeSourceOver. If the image is fully opaque
// it works out the same as NSCompositeCopy.
drawingOp = NSCompositeSourceOver;
break;
// FIXME: implement more raster ops
default:
wxLogDebug(wxT("wxCocoa does not support blitting with raster operation %d."), logicalFunc);
// Just use the default operation.
drawingOp = NSCompositeCopy;
}
wxLogTrace(wxTRACE_COCOA,wxT("[m_cocoaNSImage isFlipped]=%d"), [m_cocoaNSImage isFlipped]);
[m_cocoaNSImage drawAtPoint: NSMakePoint(0,0)
[sourceImage drawAtPoint: NSMakePoint(0,0)
fromRect: NSMakeRect(xsrc,
m_selectedBitmap.GetHeight()-height-ysrc,
width, height)
operation: NSCompositeCopy // FIXME: raster ops
operation: drawingOp
fraction: 1.0];
[sourceImage release]; // It was either retained, copied, or allocated.
[context restoreGraphicsState];
return false;
}