Expose PreviewImage & custom icons to py API.

This commit mainly:

* Exposes PreviewImage struct in RNA, including ways for user to set images data.
* Adds a new kind of PreviewImage, using a file path and IMB_thumb to get image.
* Adds a new kind of custom icon using PreviewImage, unrelated to ID previews system.
* Adds a python API (utils.previews) to allow python scripts to access those custom previews/icons.

Note that loading image from files' thumbnails is done when needed (deferred loading), not
when defining the custom preview/icon.

WARNING: for release addons who would want to use this, please keep it to a strict minimum, really needed level.
We do not want our UI to explode under hundreds of different flashy icons!

For more info, see also the release notes of Blender 2.75 (http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.75/Addons)
and the example/templates featured with Blender.

Patch by Campbell (ideasman42), Inês (brita) and Bastien (mont29).

Differential Revision: https://developer.blender.org/D1255

1 files changed, 115 insertions, 36 deletions

diff --git a/source/blender/editors/interface/interface_icons.c b/source/blender/editors/interface/interface_icons.c
index 6536c0a869e..7c05d5f4378 100644
--- a/source/blender/editors/interface/interface_icons.c
+++ b/source/blender/editors/interface/interface_icons.c
@@ -55,6 +55,7 @@
 
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
+#include "IMB_thumbs.h"
 
 #include "BIF_gl.h"
 #include "BIF_glutil.h"
@@ -904,10 +905,13 @@ void UI_icons_init(int first_dyn_id)
 static int preview_render_size(enum eIconSizes size)
 {
 	switch (size) {
-		case ICON_SIZE_ICON:    return 32;
-		case ICON_SIZE_PREVIEW: return PREVIEW_DEFAULT_HEIGHT;
+		case ICON_SIZE_ICON:
+			return ICON_RENDER_DEFAULT_HEIGHT;
+		case ICON_SIZE_PREVIEW:
+			return PREVIEW_RENDER_DEFAULT_HEIGHT;
+		default:
+			return 0;
 	}
-	return 0;
 }
 
 /* Create rect for the icon
@@ -923,12 +927,49 @@ static void icon_create_rect(struct PreviewImage *prv_img, enum eIconSizes size)
 	else if (!prv_img->rect[size]) {
 		prv_img->w[size] = render_size;
 		prv_img->h[size] = render_size;
-		prv_img->changed[size] = 1;
+		prv_img->flag[size] |= PRV_CHANGED;
 		prv_img->changed_timestamp[size] = 0;
 		prv_img->rect[size] = MEM_callocN(render_size * render_size * sizeof(unsigned int), "prv_rect");
 	}
 }
 
+void ui_icon_ensure_deferred(const bContext *C, const int icon_id, const bool big)
+{
+	Icon *icon = BKE_icon_get(icon_id);
+
+	if (icon) {
+		DrawInfo *di = (DrawInfo *)icon->drawinfo;
+
+		if (!di) {
+			di = icon_create_drawinfo();
+
+			icon->drawinfo = di;
+			icon->drawinfo_free = UI_icons_free_drawinfo;
+		}
+
+		if (di) {
+			if (di->type == ICON_TYPE_PREVIEW) {
+				PreviewImage *prv = (icon->type != 0) ? BKE_previewimg_id_ensure((ID *)icon->obj) : icon->obj;
+
+				if (prv) {
+					const int size = big ? ICON_SIZE_PREVIEW : ICON_SIZE_ICON;
+
+					if (!prv->use_deferred || prv->rect[size] || (prv->flag[size] & PRV_USER_EDITED)) {
+						return;
+					}
+
+					icon_create_rect(prv, size);
+
+					/* Always using job (background) version. */
+					ED_preview_icon_job(C, prv, NULL, prv->rect[size], prv->w[size], prv->h[size]);
+
+					prv->flag[size] &= ~PRV_CHANGED;
+				}
+			}
+		}
+	}
+}
+
 /* only called when icon has changed */
 /* only call with valid pointer from UI_icon_draw */
 static void icon_set_image(
@@ -940,6 +981,11 @@ static void icon_set_image(
 		return;
 	}
 
+	if (prv_img->flag[size] & PRV_USER_EDITED) {
+		/* user-edited preview, do not auto-update! */
+		return;
+	}
+
 	icon_create_rect(prv_img, size);
 
 	if (use_job) {
@@ -961,22 +1007,32 @@ PreviewImage *UI_icon_to_preview(int icon_id)
 	
 	if (icon) {
 		DrawInfo *di = (DrawInfo *)icon->drawinfo;
-		if (di && di->data.buffer.image) {
-			ImBuf *bbuf;
-			
-			bbuf = IMB_ibImageFromMemory(di->data.buffer.image->datatoc_rect, di->data.buffer.image->datatoc_size, IB_rect, NULL, "<matcap buffer>");
-			if (bbuf) {
-				PreviewImage *prv = BKE_previewimg_create();
-				
-				prv->rect[0] = bbuf->rect;
+		if (di) {
+			if (di->type == ICON_TYPE_PREVIEW) {
+				PreviewImage *prv = (icon->type != 0) ? BKE_previewimg_id_ensure((ID *)icon->obj) : icon->obj;
 
-				prv->w[0] = bbuf->x;
-				prv->h[0] = bbuf->y;
-				
-				bbuf->rect = NULL;
-				IMB_freeImBuf(bbuf);
-				
-				return prv;
+				if (prv) {
+					return BKE_previewimg_copy(prv);
+				}
+			}
+			else if (di->data.buffer.image) {
+				ImBuf *bbuf;
+
+				bbuf = IMB_ibImageFromMemory(di->data.buffer.image->datatoc_rect, di->data.buffer.image->datatoc_size,
+				                             IB_rect, NULL, __func__);
+				if (bbuf) {
+					PreviewImage *prv = BKE_previewimg_create();
+
+					prv->rect[0] = bbuf->rect;
+
+					prv->w[0] = bbuf->x;
+					prv->h[0] = bbuf->y;
+
+					bbuf->rect = NULL;
+					IMB_freeImBuf(bbuf);
+
+					return prv;
+				}
 			}
 		}
 	}
@@ -987,6 +1043,10 @@ static void icon_draw_rect(float x, float y, int w, int h, float UNUSED(aspect),
                            unsigned int *rect, float alpha, const float rgb[3], const bool is_preview)
 {
 	ImBuf *ima = NULL;
+	int draw_w = w;
+	int draw_h = h;
+	int draw_x = x;
+	int draw_y = y;
 
 	/* sanity check */
 	if (w <= 0 || h <= 0 || w > 2000 || h > 2000) {
@@ -1006,21 +1066,34 @@ static void icon_draw_rect(float x, float y, int w, int h, float UNUSED(aspect),
 	}
 
 	/* rect contains image in 'rendersize', we only scale if needed */
-	if (rw != w && rh != h) {
+	if (rw != w || rh != h) {
+		/* preserve aspect ratio and center */
+		if (rw > rh) {
+			draw_w = w;
+			draw_h = (int)(((float)rh / (float)rw) * (float)w);
+			draw_y += (h - draw_h) / 2;
+		}
+		else if (rw < rh) {
+			draw_w = (int)(((float)rw / (float)rh) * (float)h);
+			draw_h = h;
+			draw_x += (w - draw_w) / 2;
+		}
+		/* if the image is squared, the draw_ initialization values are good */
+
 		/* first allocate imbuf for scaling and copy preview into it */
 		ima = IMB_allocImBuf(rw, rh, 32, IB_rect);
 		memcpy(ima->rect, rect, rw * rh * sizeof(unsigned int));
-		IMB_scaleImBuf(ima, w, h); /* scale it */
+		IMB_scaleImBuf(ima, draw_w, draw_h); /* scale it */
 		rect = ima->rect;
 	}
 
 	/* draw */
 	if (is_preview) {
-		glaDrawPixelsSafe(x, y, w, h, w, GL_RGBA, GL_UNSIGNED_BYTE, rect);
+		glaDrawPixelsSafe(draw_x, draw_y, draw_w, draw_h, draw_w, GL_RGBA, GL_UNSIGNED_BYTE, rect);
 	}
 	else {
-		glRasterPos2f(x, y);
-		glDrawPixels(w, h, GL_RGBA, GL_UNSIGNED_BYTE, rect);
+		glRasterPos2f(draw_x, draw_y);
+		glDrawPixels(draw_w, draw_h, GL_RGBA, GL_UNSIGNED_BYTE, rect);
 	}
 
 	if (ima)
@@ -1081,10 +1154,13 @@ static void icon_draw_texture(
 static int get_draw_size(enum eIconSizes size)
 {
 	switch (size) {
-		case ICON_SIZE_ICON: return ICON_DEFAULT_HEIGHT;
-		case ICON_SIZE_PREVIEW: return PREVIEW_DEFAULT_HEIGHT;
+		case ICON_SIZE_ICON:
+			return ICON_DEFAULT_HEIGHT;
+		case ICON_SIZE_PREVIEW:
+			return PREVIEW_DEFAULT_HEIGHT;
+		default:
+			return 0;
 	}
-	return 0;
 }
 
 
@@ -1147,9 +1223,12 @@ static void icon_draw_size(
 		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 	}
 	else if (di->type == ICON_TYPE_PREVIEW) {
-		PreviewImage *pi = BKE_previewimg_get((ID *)icon->obj);
+		PreviewImage *pi = (icon->type != 0) ? BKE_previewimg_id_ensure((ID *)icon->obj) : icon->obj;
 
 		if (pi) {
+			/* Do deferred loading/generation if needed. */
+//			BKE_previewimg_ensure(pi, size);
+
 			/* no create icon on this level in code */
 			if (!pi->rect[size]) return;  /* something has gone wrong! */
 			
@@ -1164,17 +1243,17 @@ static void icon_draw_size(
 static void ui_id_preview_image_render_size(
         const bContext *C, Scene *scene, ID *id, PreviewImage *pi, int size, const bool use_job)
 {
-	if ((pi->changed[size] || !pi->rect[size])) { /* changed only ever set by dynamic icons */
+	if (((pi->flag[size] & PRV_CHANGED) || !pi->rect[size])) { /* changed only ever set by dynamic icons */
 		/* create the rect if necessary */
 		icon_set_image(C, scene, id, pi, size, use_job);
 
-		pi->changed[size] = 0;
+		pi->flag[size] &= ~PRV_CHANGED;
 	}
 }
 
 void UI_id_icon_render(const bContext *C, Scene *scene, ID *id, const bool big, const bool use_job)
 {
-	PreviewImage *pi = BKE_previewimg_get(id);
+	PreviewImage *pi = BKE_previewimg_id_ensure(id);
 
 	if (pi) {
 		if (big)
@@ -1186,7 +1265,7 @@ void UI_id_icon_render(const bContext *C, Scene *scene, ID *id, const bool big,
 
 static void ui_id_brush_render(const bContext *C, ID *id)
 {
-	PreviewImage *pi = BKE_previewimg_get(id); 
+	PreviewImage *pi = BKE_previewimg_id_ensure(id);
 	enum eIconSizes i;
 	
 	if (!pi)
@@ -1195,9 +1274,9 @@ static void ui_id_brush_render(const bContext *C, ID *id)
 	for (i = 0; i < NUM_ICON_SIZES; i++) {
 		/* check if rect needs to be created; changed
 		 * only set by dynamic icons */
-		if ((pi->changed[i] || !pi->rect[i])) {
+		if (((pi->flag[i] & PRV_CHANGED) || !pi->rect[i])) {
 			icon_set_image(C, NULL, id, pi, i, true);
-			pi->changed[i] = 0;
+			pi->flag[i] &= ~PRV_CHANGED;
 		}
 	}
 }
@@ -1208,7 +1287,7 @@ static int ui_id_brush_get_icon(const bContext *C, ID *id)
 	Brush *br = (Brush *)id;
 
 	if (br->flag & BRUSH_CUSTOM_ICON) {
-		BKE_icon_getid(id);
+		BKE_icon_id_ensure(id);
 		ui_id_brush_render(C, id);
 	}
 	else {
@@ -1270,7 +1349,7 @@ int ui_id_icon_get(const bContext *C, ID *id, const bool big)
 		case ID_IM: /* fall through */
 		case ID_WO: /* fall through */
 		case ID_LA: /* fall through */
-			iconid = BKE_icon_getid(id);
+			iconid = BKE_icon_id_ensure(id);
 			/* checks if not exists, or changed */
 			UI_id_icon_render(C, NULL, id, big, true);
 			break;