df21e20f65
Although we use GLib internally in Cogl we would rather not leak GLib api through Cogl's own api, except through explicitly namespaced cogl_glib_ / cogl_gtype_ feature apis. One of the benefits we see to not leaking GLib through Cogl's public API is that documentation for Cogl won't need to first introduce the Glib API to newcomers, thus hopefully lowering the barrier to learning Cogl. This patch provides a Cogl specific typedef for reporting runtime errors which by no coincidence matches the typedef for GError exactly. If Cogl is built with --enable-glib (default) then developers can even safely assume that a CoglError is a GError under the hood. This patch also enforces a consistent policy for when NULL is passed as an error argument and an error is thrown. In this case we log the error and abort the application, instead of silently ignoring it. In common cases where nothing has been implemented to handle a particular error and/or where applications are just printing the error and aborting themselves then this saves some typing. This also seems more consistent with language based exceptions which usually cause a program to abort if they are not explicitly caught (which passing a non-NULL error signifies in this case) Since this policy for NULL error pointers is stricter than the standard GError convention, there is a clear note in the documentation to warn developers that are used to using the GError api. Reviewed-by: Neil Roberts <neil@linux.intel.com> (cherry picked from commit b068d5ea09ab32c37e8c965fc8582c85d1b2db46) Note: Since we can't change the Cogl 1.x api the patch was changed to not rename _error_quark() functions to be _error_domain() functions and although it's a bit ugly, instead of providing our own CoglError type that's compatible with GError we simply #define CoglError to GError unless Cogl is built with glib disabled. Note: this patch does technically introduce an API break since it drops the cogl_error_get_type() symbol generated by glib-mkenum (Since the CoglError enum was replaced by a CoglSystemError enum) but for now we are assuming that this will not affect anyone currently using the Cogl API. If this does turn out to be a problem in practice then we would be able to fix this my manually copying an implementation of cogl_error_get_type() generated by glib-mkenum into a compatibility source file and we could also define the original COGL_ERROR_ enums for compatibility too. Note: another minor concern with cherry-picking this patch to the 1.14 branch is that an api scanner would be lead to believe that some APIs have changed, and for example the gobject-introspection parser which understands the semantics of GError will not understand the semantics of CoglError. We expect most people that have tried to use gobject-introspection with Cogl already understand though that it is not well suited to generating bindings of the Cogl api anyway and we aren't aware or anyone depending on such bindings for apis involving GErrors. (GnomeShell only makes very-very minimal use of Cogl via the gjs bindings for the cogl_rectangle and cogl_color apis.) The main reason we have cherry-picked this patch to the 1.14 branch even given the above concerns is that without it it would become very awkward for us to cherry-pick other beneficial patches from master.
84 lines
2.4 KiB
C
84 lines
2.4 KiB
C
#include <cogl/cogl.h>
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#include <glib.h>
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#include <stdio.h>
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typedef struct _Data
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{
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CoglContext *ctx;
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CoglFramebuffer *fb;
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CoglPrimitive *triangle;
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CoglPipeline *pipeline;
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} Data;
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static CoglBool
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paint_cb (void *user_data)
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{
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Data *data = user_data;
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cogl_framebuffer_clear4f (data->fb, COGL_BUFFER_BIT_COLOR, 0, 0, 0, 1);
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cogl_framebuffer_draw_primitive (data->fb, data->pipeline, data->triangle);
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cogl_onscreen_swap_buffers (COGL_ONSCREEN (data->fb));
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/* If the driver can deliver swap complete events then we can remove
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* the idle paint callback until we next get a swap complete event
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* otherwise we keep the idle paint callback installed and simply
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* paint as fast as the driver will allow... */
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if (cogl_has_feature (data->ctx, COGL_FEATURE_ID_SWAP_BUFFERS_EVENT))
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return FALSE; /* remove the callback */
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else
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return TRUE;
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}
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static void
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swap_complete_cb (CoglFramebuffer *framebuffer, void *user_data)
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{
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g_idle_add (paint_cb, user_data);
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}
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int
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main (int argc, char **argv)
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{
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Data data;
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CoglOnscreen *onscreen;
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CoglError *error = NULL;
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CoglVertexP2C4 triangle_vertices[] = {
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{0, 0.7, 0xff, 0x00, 0x00, 0x80},
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{-0.7, -0.7, 0x00, 0xff, 0x00, 0xff},
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{0.7, -0.7, 0x00, 0x00, 0xff, 0xff}
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};
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GSource *cogl_source;
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GMainLoop *loop;
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data.ctx = cogl_context_new (NULL, &error);
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if (!data.ctx) {
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fprintf (stderr, "Failed to create context: %s\n", error->message);
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return 1;
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}
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onscreen = cogl_onscreen_new (data.ctx, 640, 480);
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cogl_onscreen_show (onscreen);
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data.fb = COGL_FRAMEBUFFER (onscreen);
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cogl_onscreen_set_resizable (onscreen, TRUE);
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data.triangle = cogl_primitive_new_p2c4 (data.ctx,
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COGL_VERTICES_MODE_TRIANGLES,
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3, triangle_vertices);
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data.pipeline = cogl_pipeline_new (data.ctx);
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cogl_source = cogl_glib_source_new (data.ctx, G_PRIORITY_DEFAULT);
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g_source_attach (cogl_source, NULL);
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if (cogl_has_feature (data.ctx, COGL_FEATURE_ID_SWAP_BUFFERS_EVENT))
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cogl_onscreen_add_swap_buffers_callback (COGL_ONSCREEN (data.fb),
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swap_complete_cb, &data);
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g_idle_add (paint_cb, &data);
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loop = g_main_loop_new (NULL, TRUE);
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g_main_loop_run (loop);
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return 0;
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}
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