How to draw text in NPAPI plugin CGContextRef? - plugins

Question

I want to draw text in the NPAPI plugin CGContextRef, but i don’t know to make it work.
I get the CGContext Ref as follow:
int16_t NPP_HandleEvent(NPP instance, void* event)
{
int16_t iRet = 0;
PluginObject *obj = (PluginObject *)instance->pdata;
NPCocoaEvent *cocoaEvent = (NPCocoaEvent *)event;
switch(cocoaEvent->type)
{
case NPCocoaEventDrawRect:
obj->m_NPContext = CGContextRetain(cocoaEvent->data.draw.context);
DrawSealOnContext(obj->m_NPContext, obj->m_pstSealAPInfo);
iRet = 1;
break;
default:
iRet = 0;
break;
}
return iRet;
}
In function DrawSealOnContext, I want to draw an Ellipse and some text in the window. the function as follow:
int DrawSealOnContext(CGContextRef contextRef, PSEAL_APPEARANCE_INFO pstSealAPInfo)
{
// draw ellipses
CGRect rect = {2, 25, 146, 100};
CGContextSetLineWidth(contextRef, 4.0);
CGContextSetStrokeColorWithColor(contextRef, [NSColor blueColor].CGColor);
CGContextBeginPath(contextRef);
CGContextAddEllipseInRect(contextRef, rect);
CGContextDrawPath(contextRef, kCGPathStroke);
// draw text
CGContextSetFillColorWithColor(contextRef, [NSColor blueColor].CGColor);
NSMutableParagraphStyle * paragraphStyle = [[[NSParagraphStyle defaultParagraphStyle] mutableCopy] autorelease];
[paragraphStyle setAlignment:NSCenterTextAlignment];
NSDictionary * attributes = [NSDictionary dictionaryWithObject:paragraphStyle
forKey:NSParagraphStyleAttributeName];
NSString * mystr = #“hello\n and";
NSRect strFrame = { { 0, 0 }, { 150, 150 } };
[mystr drawInRect:strFrame withAttributes:attributes];
}
I can get the ellipse on the screen, but the text doesn’t show up?
I also try this:
// draw text
CGContextShowText(contextRef, "hello", 5);
It doesn’t work either.
what’s wrong with my program, really appreciate your
answers.

Answer 1

I have solve this problem, with the help of this article:
http://www.cocoabuilder.com/archive/cocoa/240527-setting-cgcontextref-to-the-current-context.html
The problem is that, function
[mystr drawInRect:strFrame withAttributes:attributes];
draw test in current context, but my current is not the the context "CGContextRef contextRef" i decleared. So, before i used drawInRect method, i need to set contextRef my current context.
How to set CGContextRef to current context, please refer to the website i pasted.
Hope this answer can solve your problem!