Update

subprojects/gst-python/old_examples/buffer-draw.py

@@ -0,0 +1,138 @@
+#!/usr/bin/env python
+
+import sys
+import traceback
+from math import pi
+
+import pygtk
+pygtk.require ("2.0")
+import gobject
+gobject.threads_init()
+
+import pygst
+pygst.require('0.10')
+import gst
+
+import cairo
+
+WIDTH, HEIGHT = 640, 480
+FRAMES = 300
+FRAMERATE = 15
+
+class PyGstBufferDraw(gst.Element):
+    _sinkpadtemplate = gst.PadTemplate ("sink",
+                                         gst.PAD_SINK,
+                                         gst.PAD_ALWAYS,
+                                         gst.caps_from_string ("video/x-raw-rgb,bpp=32,depth=32,blue_mask=-16777216,green_mask=16711680, red_mask=65280, alpha_mask=255,width=[ 1, 2147483647 ],height=[ 1, 2147483647 ],framerate=[ 0/1, 2147483647/1 ]"))
+    _srcpadtemplate = gst.PadTemplate ("src",
+                                         gst.PAD_SRC,
+                                         gst.PAD_ALWAYS,
+                                         gst.caps_from_string ("video/x-raw-rgb,bpp=32,depth=32,blue_mask=-16777216,green_mask=16711680, red_mask=65280, alpha_mask=255,width=[ 1, 2147483647 ],height=[ 1, 2147483647 ],framerate=[ 0/1, 2147483647/1 ]"))
+
+    def __init__(self):
+        gst.Element.__init__(self)
+
+        self.sinkpad = gst.Pad(self._sinkpadtemplate, "sink")
+        self.sinkpad.set_chain_function(self.chainfunc)
+        self.sinkpad.set_event_function(self.eventfunc)
+        self.sinkpad.set_getcaps_function(gst.Pad.proxy_getcaps)
+        self.sinkpad.set_setcaps_function(gst.Pad.proxy_setcaps)
+        self.add_pad (self.sinkpad)
+
+        self.srcpad = gst.Pad(self._srcpadtemplate, "src")
+
+        self.srcpad.set_event_function(self.srceventfunc)
+        self.srcpad.set_query_function(self.srcqueryfunc)
+        self.srcpad.set_getcaps_function(gst.Pad.proxy_getcaps)
+        self.srcpad.set_setcaps_function(gst.Pad.proxy_setcaps)
+        self.add_pad (self.srcpad)
+
+    def chainfunc(self, pad, buffer):
+        try:
+            outbuf = buffer.copy_on_write ()
+            self.draw_on (outbuf)
+            return self.srcpad.push (outbuf)
+        except:
+            return GST_FLOW_ERROR
+
+    def eventfunc(self, pad, event):
+        return self.srcpad.push_event (event)
+        
+    def srcqueryfunc (self, pad, query):
+        return self.sinkpad.query (query)
+    def srceventfunc (self, pad, event):
+        return self.sinkpad.push_event (event)
+
+    def draw_on (self, buf):
+        try:
+            caps = buf.get_caps()
+            width = caps[0]['width']
+            height = caps[0]['height']
+            framerate = caps[0]['framerate']
+            surface = cairo.ImageSurface.create_for_data (buf, cairo.FORMAT_ARGB32, width, height, 4 * width)
+            ctx = cairo.Context(surface)
+        except:
+            print "Failed to create cairo surface for buffer"
+            traceback.print_exc()
+            return
+
+        try:
+            center_x = width/4
+            center_y = 3*height/4
+
+            # draw a circle
+            radius = float (min (width, height)) * 0.25
+            ctx.set_source_rgba (0.0, 0.0, 0.0, 0.9)
+            ctx.move_to (center_x, center_y)
+            ctx.arc (center_x, center_y, radius, 0, 2.0*pi)
+            ctx.close_path()
+            ctx.fill()
+            ctx.set_source_rgba (1.0, 1.0, 1.0, 1.0)
+            ctx.set_font_size(0.3 * radius)
+            txt = "Hello World"
+            extents = ctx.text_extents (txt)
+            ctx.move_to(center_x - extents[2]/2, center_y + extents[3]/2)
+            ctx.text_path(txt)
+            ctx.fill()
+
+        except:
+            print "Failed cairo render"
+            traceback.print_exc()
+
+gobject.type_register(PyGstBufferDraw)
+
+pipe = gst.Pipeline()
+vt = gst.element_factory_make ("videotestsrc")
+cf = gst.element_factory_make ("capsfilter")
+c1 = PyGstBufferDraw()
+color = gst.element_factory_make ("ffmpegcolorspace")
+scale = gst.element_factory_make ("videoscale")
+q1 = gst.element_factory_make ("queue")
+sink = gst.element_factory_make ("autovideosink")
+
+caps = gst.caps_from_string ("video/x-raw-rgb,width=%d,height=%d,framerate=%d/1" % (WIDTH, HEIGHT, FRAMERATE))
+cf.set_property ("caps", caps)
+
+vt.set_property ("num-buffers", FRAMES)
+
+pipe.add (vt, cf, c1, q1, color, scale, sink)
+gst.element_link_many (vt, cf, c1, q1, color, scale, sink)
+
+def on_eos (bus, msg):
+    mainloop.quit()
+
+bus = pipe.get_bus()
+bus.add_signal_watch()
+bus.connect('message::eos', on_eos)
+
+pipe.set_state (gst.STATE_PLAYING)
+
+mainloop = gobject.MainLoop()
+try:
+    mainloop.run()
+except:
+    pass
+
+pipe.set_state (gst.STATE_NULL)
+pipe.get_state (gst.CLOCK_TIME_NONE)
+