GTK rotating image (pixbuf) patch

You must insert an image in the project and rotate it at any angle. The GTK version I used is windows32bit 2.24, which is from the official website. In this version of API, the rotate pixbuf API has only one simple function that rotates at a factor of 90 °: gdk_pixbuf_rotate_simple (), there is no function to rotate any angle. After one day, Google finally solved the problem. The method is as follows:

Step 1.

Found this bug, his attachment achieves arbitrary rotation angle, but this attachment file is incomplete, I added a gdk-pixbuf-private.h file (from here ). And modified the # include statement of these files, because the patch provided by him was originally used to compile GTK, but the gtk I used has been compiled and cannot be re-compiled by myself, therefore, you must change the # include statement to use this patch as the code of your project.

Step 2.

Put the. c. H files in the patch in the same make directory and compile and run the demo that comes with the patch. The test result is as follows:

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/B6/wKiom1REX9CQbl4uAARB3o-HNYw399.jpg "Title =" image.jpg "alt =" wKiom1REX9CQbl4uAARB3o-HNYw399.jpg "/>

Is the result of running the image of the demo menu, it works!

Patch API description:

Gdk_pixbuf_rotate_matrix _ starts with some matrix tool methods, which are not important.

The most important thing is this function.

void gdk_pixbuf_rotate(GdkPixbuf*dst, gdoubledst_x, gdoubledst_y, gdouble*matrix, GdkPixbuf*src, gdoublesrc_center_x, gdoublesrc_center_y, gint*result_rect_x, gint*result_rect_y, gint*result_rect_width, gint*result_rect_height, GdkInterpTypeinterp_type);

This function converts SRC pixbuf through rotate matrix and writes it to DST pixbuf. The parameters starting with result_rect _ should be the values written by the function. I haven't used them yet. The call method can be found in the demo, or my code snippets:

MyPicture *picture = MY_PICTURE(self);MyPicturePrivate* priv = MY_PICTURE_GET_PRIVATE (picture);GdkRectangle rect;if (priv->pixbuf) {    gdouble m[4];    gdouble angle = 45./180*PI;    gdk_pixbuf_rotate_martix_fill_for_rotation(m, angle);    gdk_pixbuf_rotate_matrix_mult_number(m, 1.);    gdk_pixbuf_rotate (priv->pixbuf,        picture->width/2,        picture->height/2,        m,        priv->orignPixbuf,        picture->orignWidth/2,        picture->orignHeight/2,        &rect.x,         &rect.y,         &rect.width,         &rect.height,        GDK_INTERP_NEAREST);        gdk_draw_pixbuf (appState->pixmap,        appState->drawingArea->style->white_gc,        priv->pixbuf,        0,        0,        picture->x + appState->orignX,        picture->y + appState->orignY,         picture->width,        picture->height,        GDK_RGB_DITHER_NORMAL, 0, 0);}

Which of the following has found a better solution? Please leave a message. Thank you ~

PS: Cairo is not used to process images, because Cairo turns black in transparent areas of my project when processing PNG (unknown reason, I used Cairo to draw images on pixmap), and Cairo only supports PNG, JPG, and so on. Therefore, Cairo is not required to draw images.

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GTK rotating image (pixbuf) patch