Question

嘿所有，我试图在Gtk :: DrawingArea中绘制实时图像，就像在火车站，机场，地铁等显示器中显示的那样。

对于当前的测试目的，我已经硬编码了我的代码。

这里是

Gtk ::绘图区域宽度= 720，高度= 640。我有first.pgm和second.pgm图像，每个图像都有360 * 640维度。（是的，我将它旋转用于测试目的。）这些图像包含每个像素一个字节。

1）在拍摄单张图像时画得很好。我只是将图像读入尺寸为360 * 640 * 3的 unsigned char * buffer 。我已经这样读过了

int bufferIndex=0; 
int fileIndex=0; //just assume 
for (int i=0; i<height; i++)
{
     for (int j=0; j<width; j++)
     {
         //below three lines are for RGB purpose required in Gdk::Pixbuf
         buffer[bufferIndex++] = //File[fileIndex]; 
         buffer[bufferIndex++] = //File[fileIndex]; 
         buffer[bufferIndex++] = //File[fileIndex]; 
     }
}               

Gdk::Colorspace colorSpace = Gdk::COLORSPACE_RGB;
Gdk::Colorspace colorSpace = (Gdk::Colorspace)0;
bool has_alpha = false;
int bits_per_sample = 8;
int rowStride = 360*3; // distance between rows in bytes
Glib::RefPtr<Gdk::Pixbuf> pixBuf = Gdk::Pixbuf::create_from_data((const guint8 *) buffer,
       colorSpace, has_alpha, bits_per_sample, 360, 640, rowStride);
Glib::RefPtr<Gdk::GC> gcContext;
pixBuf->render_to_drawable(drawingArea pointer, gcContext, 0, 0, 0 , 0 , 360, 640, Gdk::RGB_DITHER_MAX, 0, 0);
//It prints the image in the left half of drawing area.

这与我的预期相同，但是当我尝试绘制两个图像时会出现问题。为此，我在缓冲区中首先读取.pgm，之后我读取了第二个.pgm（意味着总共[360 * 640 * 3] * 2个字节）现在我按照代码中所示绘制它。

Glib::RefPtr<Gdk::GC>gcContext;
Gdk::Colorspace colorSpace = Gdk::COLORSPACE_RGB;
Gdk::Colorspace colorSpace = (Gdk::Colorspace)0;
bool has_alpha = false;
int bits_per_sample = 8;
int rowStride = 360*3; // distance between rows in bytes
Glib::RefPtr<Gdk::Pixbuf> pixBuf = Gdk::Pixbuf::create_from_data((const guint8 *) buffer,
       colorSpace, has_alpha, bits_per_sample, 720, 640, rowStride);
pixBuf->render_to_drawable(drawingarea pointer, gcContext, 0, 0, 0 , 0 , 720, 640, Gdk::RGB_DITHER_MAX, 0, 0);

在这两半中，首先打印.pgm。

Answer 1

您可以使用create_from_file（）方法打开这些图像，然后复制到将要显示的其他Pixbuf。这是我的代码：

DrawingArea.h

#ifndef DRAWINGAREA_H
#define DRAWINGAREA_H

#include <gtkmm.h>


class DrawingArea : public Gtk::DrawingArea
{
public:
    DrawingArea();

protected:
    // Override default signal handler:
    virtual bool on_draw(const Cairo::RefPtr<Cairo::Context>& cr);
private:
    // 1.Pgm image
    Glib::RefPtr<Gdk::Pixbuf> image1;
    // 2.Pgm image
    Glib::RefPtr<Gdk::Pixbuf> image2;
    //Pixel buffer for display
    Glib::RefPtr<Gdk::Pixbuf> display;
    // Scale of the image
    double scale;
};
#endif // DRAWINGAREA_H

DrawingArea.cpp

#include "DrawingArea.h"

DrawingArea::DrawingArea()
{
    // Load the images
    image1 = Gdk::Pixbuf::create_from_file("first.pgm");
    image2 = Gdk::Pixbuf::create_from_file("second.pgm");
    //create a 720x640 rgb Pixbuf
    display = Gdk::Pixbuf::create(Gdk::COLORSPACE_RGB,0,8,720,640);
}
// Call when the display need to be updated
bool DrawingArea::on_draw(const Cairo::RefPtr<Cairo::Context>& cr)
{
    //copy the two images to the display Pixbuf with this function:
    //void Gdk::Pixbuf::copy_area   (int src_x,int src_y,int width,int height,const Glib::RefPtr< Gdk::Pixbuf >& dest_pixbuf,int dest_x,int dest_y)     
    image1->copy_area(0,0,360,640,display,0,0);
    image2->copy_area(0,0,360,640,display,360,0);
    // Place the display Pixbuf at the center of the window
    Gdk::Cairo::set_source_pixbuf(cr, display, 0,0);
    // Update the whole drawing area
    cr->rectangle(0, 0, display->get_width(), display->get_height());
    // Fill the area with the image
    cr->fill();
    // The event has been handled.
    return true;
}

和main.cpp

#include <DrawingArea.h>
#include <gtkmm.h>


int main(int argc, char* argv[])
{
    // Initialize gtkmm and create the main window
    Glib::RefPtr<Gtk::Application> app = Gtk::Application::create(argc, argv, "betontaplfa");
    Gtk::Window window;

    // Create the drawing
    DrawingArea Dwg;
    // Insert the drawing in the window
    window.add(Dwg);
    // Resize the window
    window.resize(720,640);
    // Set the window title
    window.set_title("Pgm");
    // Show the drawing
    Dwg.show();

    // Start main loop
    return app->run(window);
}

GTKMM ::使用GTk :: Drawing区域中的单个Gdk :: PixBuf绘制多个图像

1 个答案: