charts: add vwm_chart_render_as_{pixmap,ximage}()

Preparatory work for supporting --snapshot-on-sigchld to vmon;
add a way to access a chart's pixels outside of the X server.

2 files changed, 44 insertions, 1 deletions

diff --git a/src/charts.c b/src/charts.c
index a94714b..fddef35 100644
--- a/src/charts.c
+++ b/src/charts.c
@@ -214,7 +214,7 @@ static Picture create_picture(vwm_charts_t *charts, unsigned width, unsigned hei
 
 
 /* convenience helper for creating a filled picture, supply res_pixmap to keep a reference to the pixmap drawable. */
-static Picture create_picture_fill(vwm_charts_t *charts, unsigned width, unsigned height, unsigned depth, unsigned long attrs_mask, XRenderPictureAttributes *attrs, XRenderColor *color, Pixmap *res_pixmap)
+static Picture create_picture_fill(vwm_charts_t *charts, unsigned width, unsigned height, unsigned depth, unsigned long attrs_mask, XRenderPictureAttributes *attrs, const XRenderColor *color, Pixmap *res_pixmap)
 {
 	vwm_xserver_t	*xserver = charts->xserver;
 	Picture		picture;
@@ -1172,6 +1172,47 @@ void vwm_chart_render(vwm_charts_t *charts, vwm_chart_t *chart, int op, Picture
 }
 
 
+/* render the chart into a newly allocated pixmap, intended for snapshotting purposes */
+void vwm_chart_render_as_pixmap(vwm_charts_t *charts, vwm_chart_t *chart, const XRenderColor *bg_color, Pixmap *res_pixmap)
+{
+	static const XRenderColor	blackness = { 0x0000, 0x0000, 0x0000, 0xFFFF};
+	Picture			 	dest;
+
+	assert(charts);
+	assert(chart);
+	assert(res_pixmap);
+
+	if (!bg_color)
+		bg_color = &blackness;
+
+	dest = create_picture_fill(charts, chart->width, chart->height, 32, 0, NULL, bg_color, res_pixmap);
+	vwm_chart_render(charts, chart, PictOpOver, dest, 0, 0, chart->width, chart->height);
+	XRenderFreePicture(charts->xserver->display, dest);
+}
+
+
+void vwm_chart_render_as_ximage(vwm_charts_t *charts, vwm_chart_t *chart, const XRenderColor *bg_color, XImage **res_ximage)
+{
+	Pixmap	dest_pixmap;
+
+	assert(charts);
+	assert(chart);
+	assert(res_ximage);
+
+	vwm_chart_render_as_pixmap(charts, chart, bg_color, &dest_pixmap);
+	*res_ximage = XGetImage(charts->xserver->display,
+				dest_pixmap,
+				0,
+				0,
+				chart->width,
+				chart->height,
+				AllPlanes,
+				ZPixmap);
+
+	XFreePixmap(charts->xserver->display, dest_pixmap);
+}
+
+
 /* increase the sample rate relative to current using the table of intervals */
 void vwm_charts_rate_increase(vwm_charts_t *charts)
 {
diff --git a/src/charts.h b/src/charts.h
index 222b968..ed71fdd 100644
--- a/src/charts.h
+++ b/src/charts.h
@@ -22,5 +22,7 @@ void vwm_chart_reset_snowflakes(vwm_charts_t *charts, vwm_chart_t *chart);
 int vwm_chart_set_visible_size(vwm_charts_t *charts, vwm_chart_t *chart, int width, int height);
 void vwm_chart_compose(vwm_charts_t *charts, vwm_chart_t *chart, XserverRegion *res_damaged_region);
 void vwm_chart_render(vwm_charts_t *charts, vwm_chart_t *chart, int op, Picture dest, int x, int y, int width, int height);
+void vwm_chart_render_as_pixmap(vwm_charts_t *charts, vwm_chart_t *chart, const XRenderColor *bg_color, Pixmap *res_pixmap);
+void vwm_chart_render_as_ximage(vwm_charts_t *charts, vwm_chart_t *chart, const XRenderColor *bg_color, XImage **res_ximage);
 
 #endif