contrast, transparency, brightness...

**Noxxik** · 27th February 2009, 19:27

Hi could someone help me, how I can set contrast, transparency, brightness, etc. of my QGraphicsItem or QPixmap or QImage, which are used as bruch of QGraphicsItem.
Thanks a lot

**Noxxik** · 28th February 2009, 14:23

nobody gives me hint? please

**aamer4yu** · 28th February 2009, 19:55

Transparency is easy,,, just use QColor(r,g,b,a); a is for aplha, meaning how much transparent pixel shud be.

As for brightness, contrast,,, there was some example, probably on Qt Labs -> Dojo . am not able to find the link,, but will post if i find it. You can search for it meanwhile , may be u find it

**Noxxik** · 28th February 2009, 20:13

for transparency and QColor(r,g,b,a); I thought, that QColor is usable only for colors. So if it is usable for QPixmap and QImage too, It is great

I can try it
And If you find this link you will be my God

**aamer4yu** · 28th February 2009, 20:41

Transparency is easy,,, just use QColor(r,g,b,a); a is for aplha, meaning how much transparent pixel shud be.

Sorry about this, I looked up Qimage and found it uses QRgb in setPixel

However transparency is still easy... you can use QGraphicsItem::setOpacity

**Noxxik** · 28th February 2009, 21:51

Originally Posted by aamer4yu

Sorry about this, I looked up Qimage and found it uses QRgb in setPixel

However transparency is still easy... you can use QGraphicsItem::setOpacity

but QGraphicsItem::setOpacity it is not, only QPainter::setOpacity and I am trying QImage::colorTable now, but I dont know, if it is OK

**Noxxik** · 28th February 2009, 22:29

I am in this situation...

Qt Code:

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QImage image = item->brush().textureImage();
        QVector<QRgb> rgbvector = image.colorTable();
 
        QVector<QColor> colors(0);
        QVector<QRgb> rgbvector2(0);
        foreach(QRgb pixel, rgbvector){
            colors.append(pixel);
        }
        foreach(QColor color, colors){
            color.setAlpha(value);
            rgbvector2.append(color.rgba());
        }
        image.setColorTable(rgbvector2);
 
        item->setBrush(QBrush(image));

QImage image = item->brush().textureImage();
        QVector<QRgb> rgbvector = image.colorTable();

        QVector<QColor> colors(0);
        QVector<QRgb> rgbvector2(0);
        foreach(QRgb pixel, rgbvector){
            colors.append(pixel);
        }
        foreach(QColor color, colors){
            color.setAlpha(value);
            rgbvector2.append(color.rgba());
        }
        image.setColorTable(rgbvector2);

        item->setBrush(QBrush(image));

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but anything changes. It is some mistake in this code or in another? thanks for reaction