Question

颜色具有QImage rgba组件的值，我们在QImage中标记此颜色并读取m_color(QColor(0,127,0,100); m_pen.setColor(m_color); //set Qpen color m_painter.setPen(m_pen); m_painter.setCompositionMode(QPainter::CompositionMode_Source); painter->drawPixmap(Qpoint(0,0),*m_Pixmap);//m_Pixmap is QPixmap m_painter.drawline(initialpoint,finalpoint);// draw line over transparent pixmap item QImage img =m_Pixmap->toImage; for (int i=0;i<img.height();i++) //col { for(int j=0;j<img.width();j++) //row { qDebug()<<qGreen(img.pixel(j,i)); /// it return 50 during traverse painter line else give 0/// but it should return 127 as red component is 127 ///code } if(QColor(img.pixel(j,i)==m_color)/// its never true// it should true during traverse the line draw by painter on pixmap ///code } } }的像素的红色，它给出不同的值，即它给出红色分量= 50。

码

var checkboxValues = JSON.parse(localStorage.getItem('checkboxValues')) || {},
  $checkboxes = $("#checkbox-container :checkbox");

$checkboxes.on("change", function() {
  $checkboxes.each(function() {
    checkboxValues[this.id] = this.checked;
  });
  localStorage.setItem("checkboxValues", JSON.stringify(checkboxValues));
});

// On page load
$.each(checkboxValues, function(key, value) {
  $("#" + key).prop('checked', value);
  if(value){
  	$("#" + key).parent('label').css('background', 'yellow');
  }
  
});

没有任何东西设置为画家它直接绘制线...当m_color具有没有alpha值的颜色或者如果alpha为255时，颜色匹配为真

Answer 1

根据Qt4文档，m_Pixmap-＆gt; toImage将返回没有Alpha通道的RGB32图像。 Dataformat是0xFFRRGGBB。所以Alpha总是255。

http://doc.qt.io/qt-4.8/qpixmap.html#toImage

将图像转换为QPixmap时，请尝试保留QImage。

如何获得正确的颜色分量，包括QImage像素的alpha值？

1 个答案: