Qt/Images/SemiTransparentPixels - Revision history

Daviddoria: /* form.cpp */

2011-11-15T15:41:58Z

‎form.cpp

Daviddoria: /* form.cpp */

2011-11-15T13:22:19Z

‎form.cpp

Daviddoria: Created page with '==main.cpp== #include #include "form.h" int main(int argc, char *argv[]) { QApplication app(argc, argv); Form form; form.show(); ret…'

2011-11-15T00:42:20Z

Created page with '==main.cpp== <source lang="cpp"> #include <QApplication> #include "form.h" int main(int argc, char *argv[]) { QApplication app(argc, argv); Form form; form.show(); ret…'

New page

==main.cpp==
<source lang="cpp">
#include <QApplication>

#include "form.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Form form;

form.show();
return app.exec();
}

</source>

==form.h==
<source lang="cpp">
#ifndef FORM_H
#define FORM_H

#include "ui_form.h"

class Form : public QWidget, private Ui::Form
{
Q_OBJECT

public:
Form(QWidget *parent = 0);

};

#endif

</source>

==form.cpp==
<source lang="cpp">
#include <QtGui>
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QPixmap>

#include "form.h"

Form::Form(QWidget *parent)
: QWidget(parent)
{
setupUi(this);

QPixmap pixmap(100,100);
QColor black(255,0,0);
pixmap.fill(black);

QBitmap alpha(100,100);
QPainter painter( &alpha);

// Set everything to opaque
painter.setPen(Qt::color0);
for(unsigned int i = 0; i < 100; ++i)
{
for(unsigned int j = 0; j < 100; ++j)
{
painter.drawPoint(i, j);
}
}

// Set the top left corner to transparent
painter.setPen(Qt::color1);
for(unsigned int i = 0; i < 50; ++i)
{
for(unsigned int j = 0; j < 50; ++j)
{
painter.drawPoint(i, j);
}
}

// Set the top right corner to semi-transparent
painter.setPen(.5);
for(unsigned int i = 51; i < 100; ++i)
{
for(unsigned int j = 0; j < 50; ++j)
{
painter.drawPoint(i, j);
}
}

// A pixel value of 1 on the mask means the pixmap's pixel is unchanged; a value of 0 means the pixel is transparent.
pixmap.setAlphaChannel(alpha);

QGraphicsScene* scene = new QGraphicsScene;
scene->addPixmap(pixmap);

this->graphicsView->setScene(scene);

}

</source>

==form.ui==
<source lang="text">
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>Form</class>
<widget class="QWidget" name="Form">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>400</width>
<height>300</height>
</rect>
</property>
<property name="windowTitle">
<string>Form</string>
</property>
<widget class="QGraphicsView" name="graphicsView">
<property name="geometry">
<rect>
<x>60</x>
<y>50</y>
<width>256</width>
<height>192</height>
</rect>
</property>
</widget>
</widget>
<resources/>
<connections/>
</ui>

</source>

==CMakeLists.txt==
<source lang="cmake">
cmake_minimum_required(VERSION 2.6)

PROJECT(QPixmapOpacity)

FIND_PACKAGE(Qt4 REQUIRED)
INCLUDE(${QT_USE_FILE})

QT4_WRAP_UI(UISrcs form.ui)
QT4_WRAP_CPP(MOCSrcs form.h)

include_directories(${include_directories} ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_BINARY_DIR})

ADD_EXECUTABLE(QPixmapOpacity main.cpp form.h form.cpp ${MOCSrcs} ${UISrcs})
TARGET_LINK_LIBRARIES(QPixmapOpacity ${QT_LIBRARIES})

</source>

@@ Line 50: / Line 50: @@
    setupUi(this);
-   QPixmap pixmap(100,100);
+   QColor transparentRed(255,0,0, 0);
-  //QColor black(0,0,0);
+   QColor semiTransparentRed(255,0,0, 127);
-   QColor red(255,0,0);
+   QColor opaqueRed(255,0,0, 255);
-   pixmap.fill(red);
-−
-  QPixmap alpha(100,100);
-  QPainter painter( &alpha);
-   // Set everything to opaque red
+   QImage image(100,100,QImage::Format_ARGB32);
-  painter.setPen(QColor( 255, 0, 0, 255 ));
+   image.fill(opaqueRed.rgba());
-   for(unsigned int i = 0; i < 100; ++i)
-−
-    for(unsigned int j = 0; j < 100; ++j)
-−
-      painter.drawPoint(i, j);
-−
-−
    // Set the top left corner to totally transparent
    for(unsigned int i = 0; i < 50; ++i)
+     {
      for(unsigned int j = 0; j < 50; ++j)
+       {
-       painter.drawPoint(i, j);
+       image.setPixel(i,j,transparentRed.rgba());
+       }
+     }
    // Set the top right corner to semi-transparent red
    for(unsigned int i = 50; i < 100; ++i)
+     {
      for(unsigned int j = 0; j < 50; ++j)
+       {
-       painter.drawPoint(i, j);
+       image.setPixel(i,j,semiTransparentRed.rgba());
+       }
+     }
    QGraphicsScene* scene = new QGraphicsScene;
    scene->addPixmap(pixmap);