Add scaled content redraw interface.

Add a new interface to the content to allow automaticaly scaled
content redraws. This is intended to replace the thumbnail_redraw
interface with something more generic.

content/content.c

@@ -33,7 +33,9 @@
 #include "content/content_protected.h"
 #include "content/hlcache.h"
 #include "image/bitmap.h"
+#include "desktop/knockout.h"
 #include "desktop/browser.h"
+#include "desktop/plotters.h"
 #include "desktop/gui_internal.h"
 #include "utils/nsoption.h"
 
@@ -551,8 +553,7 @@ void content__request_redraw(struct content *c,
 /**
  * Display content on screen with optional tiling.
  *
- * Calls the redraw_tile function for the content, or emulates it with the
+ * Calls the redraw function for the content.
- * redraw function if it doesn't exist.
  */
 
 bool content_redraw(hlcache_handle *h, struct content_redraw_data *data,
@@ -576,6 +577,74 @@ bool content_redraw(hlcache_handle *h, struct content_redraw_data *data,
 }
 
 
+/* exported interface, documented in content/content.h */
+bool content_scaled_redraw(struct hlcache_handle *h,
+		int width, int height, const struct redraw_context *ctx)
+{
+	struct content *c = hlcache_handle_get_content(h);
+	struct redraw_context new_ctx = *ctx;
+	struct rect clip;
+	struct content_redraw_data data;
+	bool plot_ok = true;
+
+	assert(c != NULL);
+
+	/* ensure it is safe to attempt redraw */
+	if (c->locked) {
+		return true;
+	}
+
+	/* ensure we have a redrawable content */
+	if (c->handler->redraw == NULL) {
+		return true;
+	}
+
+	LOG(("Content %p %dx%d ctx:%p", c, width, height, ctx));
+
+	if (ctx->plot->option_knockout) {
+		knockout_plot_start(ctx, &new_ctx);
+	}
+
+	/* Set clip rectangle to required thumbnail size */
+	clip.x0 = 0;
+	clip.y0 = 0;
+	clip.x1 = width;
+	clip.y1 = height;
+
+	new_ctx.plot->clip(&clip);
+
+	/* Plot white background */
+	plot_ok &= new_ctx.plot->rectangle(clip.x0, clip.y0, clip.x1, clip.y1,
+			plot_style_fill_white);
+
+
+	/* Set up content redraw data */
+	data.x = 0;
+	data.y = 0;
+	data.width = width;
+	data.height = height;
+
+	data.background_colour = 0xFFFFFF;
+	data.repeat_x = false;
+	data.repeat_y = false;
+
+	/* Find the scale factor to use if the content has a width */
+	if (c->width) {
+		data.scale = (float)width / (float)c->width;
+	} else {
+		data.scale = 1.0;
+	}
+
+	/* Render the content */
+	plot_ok &= c->handler->redraw(c, &data, &clip, &new_ctx);
+
+	if (ctx->plot->option_knockout) {
+		knockout_plot_end();
+	}
+
+	return plot_ok;
+}
+
 /**
  * Register a user for callbacks.
  *

content/content.h

@@ -270,6 +270,27 @@ void content_mouse_action(struct hlcache_handle *h, struct browser_window *bw,
 bool content_keypress(struct hlcache_handle *h, uint32_t key);
 bool content_redraw(struct hlcache_handle *h, struct content_redraw_data *data,
 		const struct rect *clip, const struct redraw_context *ctx);
+
+
+/**
+ * Redraw a content with scale set for horizontal fit.
+ *
+ * Redraws the content at a specified width and height with the
+ * content drawing scaled to fit within the area.
+ *
+ * \param content The content to redraw
+ * \param width The target width
+ * \param height The target height
+ * \param ctx current redraw context
+ * \return true if successful, false otherwise
+ *
+ * The thumbnail is guaranteed to be filled to its width/height extents, so
+ * there is no need to render a solid background first.
+ *
+ * Units for width and height are pixels.
+ */
+bool content_scaled_redraw(struct hlcache_handle *content, int width, int height, const struct redraw_context *ctx);
+
 void content_open(struct hlcache_handle *h, struct browser_window *bw,
 		struct content *page, struct object_params *params);
 void content_close(struct hlcache_handle *h);