How to copy pixmap and keep scale ratio?

[Teerayoot]

I need to copy portion of pixmap and fill into onscreen painter.

my code that not work

painter.drawPixmap(pixMap->rect(),*pixMap,recvMap);

painter.drawPixmap(pixMap->rect(),*pixMap,recvMap);

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the problem is image on screen is not correctly scale like original one
seem it ratio is enlarge to fit target rect.

I just need raw portion of pixmap and scale that keep image ratio.

Thank.

[marcel]

Use QPixmap::scaled() with Qt::KeepAspectRatio

[Teerayoot]

I tried but seem not got result i expected.

Portion of image not scale to full screen render area.


I copy portion of pixmap into another pixmap buffer
then make it scale

look at my code

QPixmap buffer(pixMap->rect().width(),pixMap->height() );
	QPainter painterBuffer(&buffer);
	QPainter painter(this);
 
	//painter.scale(mapScale,mapScale);
 
	int cX   = pixMap->width()/2;
	int cZ   = pixMap->height()/2;
 
 
	//myPlayer.curPos.x = myX;
	//myPlayer.curPos.z = myZ;
	int cMapX = pixMap->width()/2;
	int cMapY = pixMap->height()/2;
 
 
 
	int gamePointX=0;
	int gamePointZ=0;
 
	QRect recvMap;
	recvMap.setLeft( gamePointX + cMapX + (myX - cX/mapScale)/scale );
	recvMap.setRight( gamePointX + cMapX + (myX + cX/mapScale)/scale);
	recvMap.setTop( gamePointZ + cMapY - (myZ + cZ/mapScale)/scale);
	recvMap.setBottom(  gamePointZ + cMapY - (myZ - cZ/mapScale)/scale);
 
	painter.setRenderHint(QPainter::Antialiasing,true);
	QRectF srcRect=pixMap->rect();
 
	painter.fillRect(rect(),QBrush(Qt::black));
 
 
 
	painterBuffer.drawPixmap(QPointF(1,1),*pixMap,recvMap);
 
	buffer.scaled(512,512,Qt::KeepAspectRatio);
	painter.save();
 
	painter.drawPixmap(QPointF(1,1),buffer,buffer.rect());
 
	painter.restore();
 
	painter.setPen(Qt::white);
 
	QFont font(font());
	font.setPointSize(24);
	painter.setFont(font);
 
	QFontMetrics fm(painter.font());
	int fontHeigh = fm.height();
	QString tmp;
	tmp.sprintf("%.0f %.0f",mouseMovePos.x(),mouseMovePos.y());
	//painter.drawText(0,fontHeigh,tr("%1,%2").arg(mouseMovePos.x()).arg(mouseMovePos.y()));
	painter.drawText(0,fontHeigh,tmp);
	tmp.clear();
	tmp.sprintf("My Pos %d %d",myX,myZ);
	painter.drawText(0,fontHeigh*2,tmp);

QPixmap buffer(pixMap->rect().width(),pixMap->height() );
	QPainter painterBuffer(&buffer);
	QPainter painter(this);

	//painter.scale(mapScale,mapScale);

	int cX   = pixMap->width()/2;
	int cZ   = pixMap->height()/2;
	
	
	//myPlayer.curPos.x = myX;
	//myPlayer.curPos.z = myZ;
	int cMapX = pixMap->width()/2;
	int cMapY = pixMap->height()/2;

	

	int gamePointX=0;
	int gamePointZ=0;

	QRect recvMap;
	recvMap.setLeft( gamePointX + cMapX + (myX - cX/mapScale)/scale );
	recvMap.setRight( gamePointX + cMapX + (myX + cX/mapScale)/scale);
	recvMap.setTop( gamePointZ + cMapY - (myZ + cZ/mapScale)/scale);
	recvMap.setBottom(  gamePointZ + cMapY - (myZ - cZ/mapScale)/scale);

	painter.setRenderHint(QPainter::Antialiasing,true);
	QRectF srcRect=pixMap->rect();
	
	painter.fillRect(rect(),QBrush(Qt::black));
	
	
	
	painterBuffer.drawPixmap(QPointF(1,1),*pixMap,recvMap);

	buffer.scaled(512,512,Qt::KeepAspectRatio);
	painter.save();
	
	painter.drawPixmap(QPointF(1,1),buffer,buffer.rect());
		
	painter.restore();
	
	painter.setPen(Qt::white);
	
	QFont font(font());
	font.setPointSize(24);
	painter.setFont(font);
	
	QFontMetrics fm(painter.font());
	int fontHeigh = fm.height();
	QString tmp;
	tmp.sprintf("%.0f %.0f",mouseMovePos.x(),mouseMovePos.y());
	//painter.drawText(0,fontHeigh,tr("%1,%2").arg(mouseMovePos.x()).arg(mouseMovePos.y()));
	painter.drawText(0,fontHeigh,tmp);
	tmp.clear();
	tmp.sprintf("My Pos %d %d",myX,myZ);
	painter.drawText(0,fontHeigh*2,tmp);

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result image