Hi all:
I have some questions when I using the drawable area with the
gtk+2.0.
First, I'm building a data analyzer under thr Linux, so there is a process
to generate the data and my analyzer display the data.
My idea is to use a drawable area(I use the GtkDrawingArea) and get the pix
buffer of it by the gdk_pixbuf_get_from_drawable(), then my background
program can fill the pix buffer pix by pix.
Question 1: anytime I fill to the pixbuf, it will rendering the drawing area
immediately?
Question 2: the following code segment is what I done until now...what
should I do?
Thanks.
Dave.
this function put_pixel is referenced from the GDK Reference Manual
34 void
35 put_pixel (GdkPixbuf *pixbuf, int x, int y, guchar red, guchar green,
guchar blue, guchar alpha)
36 {
37 int width, height, rowstride, n_channels;
38 guchar *pixels, *p;
39
40 n_channels = gdk_pixbuf_get_n_channels (pixbuf);
41 g_assert (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
42 g_assert (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);
43 g_assert (gdk_pixbuf_get_has_alpha (pixbuf));
44 g_assert (n_channels == 4);
45
46 width = gdk_pixbuf_get_width (pixbuf);
47 height = gdk_pixbuf_get_height (pixbuf);
48
49 g_assert (x >= 0 && x < width);
50 g_assert (y >= 0 && y < height);
51
52 rowstride = gdk_pixbuf_get_rowstride (pixbuf);
53 pixels = gdk_pixbuf_get_pixels (pixbuf);
54
55 p = pixels + y * rowstride + x * n_channels;
56 p[0] = red;
57 p[1] = green;
58 p[2] = blue;
59 p[3] = alpha;
60 }
In the callbacks.c
function on_drawingarea_virtual_LCD_configure_event() is the callback
function of my drawing area.
151 gboolean
152 on_drawingarea_virtual_LCD_configure_event (GtkWidget
*widget,
153 GdkEventConfigure *event)
154 {
155 gint x,y;
156 GdkPixbuf* virtual_LCD_buf;
157 GdkRectangle rect;
158
159
160 if(virtual_LCD_pixmap)
161 g_object_unref(virtual_LCD_pixmap);
162
163 virtual_LCD_pixmap = gdk_pixmap_new(widget->window,
164 widget->allocation.width,
165 widget->allocation.height,
166 -1);
167
168 gdk_window_get_origin (widget->window, &x, &y);
169 rect.x = x;
170 rect.y = y;
171 gdk_drawable_get_size (GDK_DRAWABLE (widget->window), &rect.width,
172 &rect.height);
173
174 virtual_LCD_buf = gdk_pixbuf_get_from_drawable(NULL,
175 virtual_LCD_pixmap,
176
gdk_colormap_get_system(),
177 rect.x-x,
178 rect.y-y,
179 0,
180 0,
181 rect.width,
182 rect.height
183 );
184 gint i=0;
185 // I want to test the put_pixel when the drawing are establish.
186 for(i=0;i<100;i++){
187 put_pixel (virtual_LCD_buf, i, i, 255-i,255-i,255-(2*i),0);
188
189
190 }
--
System on Chip Design Lab.
Dept. of Computer Science and Information Engineering,
National Chung Cheng University
E-mail : [EMAIL PROTECTED]
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