Add image Scale for gtk119

Gtkmm3/gtk119_imageviewer2/src/MyImage.cc

@@ -1,42 +1,69 @@
 #include "MyImage.hh"
 
-MyImage::MyImage(){
+MyImage::MyImage()
-
+:scale_radio(1.0)
+{
 }
 
-MyImage::~MyImage(){
+MyImage::~MyImage()
-
+{
 }
 
-bool MyImage::on_draw(const Cairo::RefPtr<Cairo::Context> &cr){
+bool MyImage::on_draw(const Cairo::RefPtr<Cairo::Context> &cr)
-    if(!image){
+{
+    if (!image)
+    {
         return false;
     }
 
-    int width = image->get_width();
+    // Set the default size for drawing area
-    int height = image->get_height();
+    set_size_request(surface->get_width()*scale_radio, 
+                     surface->get_height()*scale_radio);
 
-    //Set the default size for drawing area
+    cr->scale(scale_radio, scale_radio);
-    set_size_request(width,height);
+    cr->set_source(surface, 0, 0);
-
-    // Draw the image in the middle of the drawing area, or (if the image is
-    // larger than the drawing area) draw the middle part of the image.
-    Gdk::Cairo::set_source_pixbuf(cr, image,
-        (width - image->get_width())/2, (height - image->get_height())/2);
 
     cr->paint();
 
     return true;
 }
 
+void MyImage::scale_draw(double scale)
+{
+    // Set the scale radio and scale
+    scale_radio = scale;
+    queue_draw();
+}
+
 void MyImage::set_pixbuf(const Glib::RefPtr<Gdk::Pixbuf> &pixbuf)
 {
-    if(image){
+    if (image)
+    {
         image.reset();
     }
 
     image = pixbuf;
 
-    //ReDraw the draw area
+    if (!surface)
+    {
+        // Create a surface
+        surface = Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32,
+                                              image->get_width(), image->get_height());
+    }
+    else
+    {
+    }
+
+    //Get Image Size
+    int width = image->get_width();
+    int height = image->get_height();
+    // Draw the image in the middle of the surface, or (if the image is
+    // larger than the drawing area) draw the middle part of the image.
+    auto cr = Cairo::Context::create(surface);
+    Gdk::Cairo::set_source_pixbuf(cr, image,
+                                  (width - image->get_width()) / 2, (height - image->get_height()) / 2);
+    cr->paint();
+
+    // ReDraw the draw area
     queue_draw();
 }

Gtkmm3/gtk119_imageviewer2/src/MyImage.hh

@@ -6,8 +6,14 @@ class MyImage : public Gtk::DrawingArea{
     public:
         MyImage();
         virtual ~MyImage();
+        //Set a Pixbuf to draw
         void set_pixbuf(const Glib::RefPtr<Gdk::Pixbuf> &pixbuf);
+        //Scale the image
+        void scale_draw(double scale);
     protected:
         bool on_draw(const Cairo::RefPtr<Cairo::Context> &cr) override;
+    private:
+        double scale_radio;
+        Cairo::RefPtr<Cairo::ImageSurface> surface;
         Glib::RefPtr<Gdk::Pixbuf> image;
 };

Gtkmm3/gtk119_imageviewer2/src/MyWin.cc

@@ -18,6 +18,7 @@ btnopen("Open Image")
     m_adjustment = Gtk::Adjustment::create(1.0,0.1,10.0,0.1,0.1);
     scale.set_default_direction(Gtk::TEXT_DIR_LTR);
     scale.set_adjustment(m_adjustment);
+    scale.signal_value_changed().connect(sigc::mem_fun(*this,&MyWin::scale_changed));
 
     //Add control widgets
     btnbox.pack_start(scale);
@@ -50,3 +51,9 @@ void MyWin::dialog_response(int response_id){
 
     dialog.reset();
 }
+
+void MyWin::scale_changed(){
+    double value = scale.get_value();
+    g_print("%f\n",value);
+    image_area.scale_draw(value);
+}

Gtkmm3/gtk119_imageviewer2/src/MyWin.hh

@@ -21,4 +21,5 @@ class MyWin : public Gtk::Window{
         //Signal Handlers
         void btnopen_clicked();
         void dialog_response(int response_id);
+        void scale_changed();
 };

cairo_scale.py

@@ -0,0 +1,60 @@
+#!/usr/bin/python3
+
+import cairo
+import gi
+gi.require_version("Gtk", "3.0")
+from gi.repository import Gtk
+
+
+def draw(da, ctx):
+    global surface
+    
+    ctx.scale(scale, scale)
+    ctx.set_source_surface(surface)
+    ctx.get_source().set_filter(cairo.FILTER_NEAREST)
+    ctx.paint()
+    
+    da.set_size_request(surface.get_width() * scale, surface.get_height() * scale)
+    
+def clicked(btn):
+    global scale
+    scale *= 1.5
+    da = btn.get_parent().get_children()[1].get_child().get_child()
+    da.queue_draw()
+
+
+def main():
+    global scale
+    scale = 1
+    
+    global surface
+    surface = cairo.ImageSurface.create_from_png("../Xe-Project/Gift.png")
+    
+    win = Gtk.Window()
+    win.connect('destroy', lambda w: Gtk.main_quit())
+    win.set_default_size(500, 500)
+    
+    box = Gtk.Box()
+    win.add(box)
+    
+    btn = Gtk.Button()
+    btn.set_label("Scale")
+    box.add(btn)
+    btn.connect('clicked', clicked)
+    
+    scrolled_win = Gtk.ScrolledWindow()
+    box.add(scrolled_win)
+
+    drawingarea = Gtk.DrawingArea()
+    drawingarea.set_vexpand(True)
+    drawingarea.set_hexpand(True)
+    scrolled_win.add(drawingarea)
+    drawingarea.connect('draw', draw)
+    
+
+    win.show_all()
+    Gtk.main()
+
+
+if __name__ == '__main__':
+    main()