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NPAPI:CoreGraphicsDrawing: Difference between revisions
→Bridging QuickDraw and CoreGraphics
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Don't worry! There is a way for plugins to draw using CoreGraphics, yet remain compatible with QuickDraw-only browsers. The idea is to use QDBeginCGContext() and QDEndCGContext() to obtain a CGContextRef for the CGrafPtr provided by the browser. We will be shipping some sample code to demonstrate this technique, but here is a little snippet for your enjoyment: | Don't worry! There is a way for plugins to draw using CoreGraphics, yet remain compatible with QuickDraw-only browsers. The idea is to use QDBeginCGContext() and QDEndCGContext() to obtain a CGContextRef for the CGrafPtr provided by the browser. We will be shipping some sample code to demonstrate this technique, but here is a little snippet for your enjoyment: | ||
static CGContextRef beginQDPluginUpdate(NPWindow *window) | static CGContextRef beginQDPluginUpdate(NPWindow *window) | ||
{ | { | ||
// window->window is an NPPort* since the browser is using QuickDraw | // window->window is an NPPort* since the browser is using QuickDraw | ||
NP_Port *npPort = ((NP_Port *)window->window); | NP_Port *npPort = ((NP_Port *)window->window); | ||
// Get the CGContext for the port | // Get the CGContext for the port | ||
CGContextRef cgContext; | CGContextRef cgContext; | ||
QDBeginCGContext(npPort->port, &cgContext); | QDBeginCGContext(npPort->port, &cgContext); | ||
CGContextSaveGState(cgContext); | CGContextSaveGState(cgContext); | ||
// Set the CG clip path to the port's clip region -- QDBeginCGContext() | |||
// Set the CG clip path to the port's clip region -- QDBeginCGContext() does not automatically respect the QuickDraw port's | // does not automatically respect the QuickDraw port's clip region. | ||
RgnHandle clipRegion = NewRgn(); | RgnHandle clipRegion = NewRgn(); | ||
GetPortClipRegion(npPort->port, clipRegion); | GetPortClipRegion(npPort->port, clipRegion); | ||
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ClipCGContextToRegion(cgContext, &portBounds, clipRegion); | ClipCGContextToRegion(cgContext, &portBounds, clipRegion); | ||
DisposeRgn(clipRegion); | DisposeRgn(clipRegion); | ||
// Flip the CG context vertically -- its origin is at the lower left, | |||
// but QuickDraw's origin is at the upper left. | |||
// Flip the CG context vertically -- its origin is at the lower left, but QuickDraw's origin is at the upper left. | |||
CGContextTranslateCTM(cgContext, 0.0, portBounds.bottom - portBounds.top); | CGContextTranslateCTM(cgContext, 0.0, portBounds.bottom - portBounds.top); | ||
CGContextScaleCTM(cgContext, 1.0, -1.0); | CGContextScaleCTM(cgContext, 1.0, -1.0); | ||
return cgContext; | return cgContext; | ||
} | } | ||
static void endQDPluginUpdate(NPWindow *window, CGContextRef cgContext) | |||
static void endQDPluginUpdate(NPWindow *window, CGContextRef cgContext) | { | ||
{ | |||
// Restore state (it was saved in beginQDPluginUpdate()) | // Restore state (it was saved in beginQDPluginUpdate()) | ||
CGContextRestoreGState(cgContext); | CGContextRestoreGState(cgContext); | ||
// If we had to prepare the CGContext for use in a QuickDraw-only browser, | // If we had to prepare the CGContext for use in a QuickDraw-only browser, | ||
// restore its state and notify QD that the CG drawing sequence is over. | // restore its state and notify QD that the CG drawing sequence is over. | ||
CGContextFlush(cgContext); | CGContextFlush(cgContext); | ||
QDEndCGContext(((NP_Port *)window->window)->port, &cgContext); | QDEndCGContext(((NP_Port *)window->window)->port, &cgContext); | ||
} | } | ||
This trick will not work once QuickDraw is removed from Mac OS X. It is intended for plugin developers that want to draw using CoreGraphics, yet remain compatible with QuickDraw-only browsers that haven't adopted these proposed NPAPI extensions. | This trick will not work once QuickDraw is removed from Mac OS X. It is intended for plugin developers that want to draw using CoreGraphics, yet remain compatible with QuickDraw-only browsers that haven't adopted these proposed NPAPI extensions. | ||