Font preview for file browser

D1002 by @plasmasolutions, with own refactoring.

Note, needed to do a bad-level call here (IMB -> BLF)
Also can't use the BLF API directly because its not thread-safe.
So keep the function isolated (blf_thumbs.c).

9 files changed, 222 insertions, 14 deletions

diff --git a/source/blender/blenfont/BLF_api.h b/source/blender/blenfont/BLF_api.h
index 206345582b2..09734bd9754 100644
--- a/source/blender/blenfont/BLF_api.h
+++ b/source/blender/blenfont/BLF_api.h
@@ -186,6 +186,12 @@ char **BLF_dir_get(int *ndir) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
 /* Free the data return by BLF_dir_get. */
 void BLF_dir_free(char **dirs, int count) ATTR_NONNULL();
 
+/* blf_thumbs.c */
+void BLF_thumb_preview(
+        const char *filename, const char **draw_str, const unsigned char draw_str_lines,
+        const float font_color[4], const int font_size,
+        unsigned char *buf, int w, int h, int channels) ATTR_NONNULL();
+
 #ifdef DEBUG
 void BLF_state_print(int fontid);
 #endif
diff --git a/source/blender/blenfont/CMakeLists.txt b/source/blender/blenfont/CMakeLists.txt
index 392a9ede100..2f10c3580e0 100644
--- a/source/blender/blenfont/CMakeLists.txt
+++ b/source/blender/blenfont/CMakeLists.txt
@@ -47,6 +47,7 @@ set(SRC
 	intern/blf_font.c
 	intern/blf_glyph.c
 	intern/blf_lang.c
+	intern/blf_thumbs.c
 	intern/blf_translation.c
 	intern/blf_util.c
 
diff --git a/source/blender/blenfont/intern/blf_thumbs.c b/source/blender/blenfont/intern/blf_thumbs.c
new file mode 100644
index 00000000000..afda6a382f9
--- /dev/null
+++ b/source/blender/blenfont/intern/blf_thumbs.c
@@ -0,0 +1,104 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Thomas Beck
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenfont/intern/blf_thumbs.c
+ *  \ingroup blf
+ *
+ * Utility function to generate font preview images.
+ *
+ * Isolate since this needs to be called by #ImBuf code (bad level call).
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <ft2build.h>
+
+#include FT_FREETYPE_H
+
+#include "BLI_utildefines.h"
+#include "BLI_listbase.h"
+#include "BLI_rect.h"
+#include "BLI_threads.h"
+
+#include "blf_internal.h"
+#include "blf_internal_types.h"
+
+#include "BLF_api.h"
+
+#include "BLI_strict_flags.h"
+
+/**
+ * This function is used for generating thumbnail previews.
+ *
+ * \note called from a thread, so it bypasses the normal BLF_* api (which isn't thread-safe).
+ */
+void BLF_thumb_preview(
+        const char *filename,
+        const char **draw_str, const unsigned char draw_str_lines,
+        const float font_color[4], const int font_size,
+        unsigned char *buf, int w, int h, int channels)
+{
+	const unsigned int dpi = 72;
+	const int font_size_min = 6;
+	int font_size_curr;
+	/* shrink 1/th each line */
+	int font_shrink = 4;
+
+	FontBLF* font;
+	int i;
+
+	/* Create a new blender font obj and fill it with default values */
+	font = blf_font_new("thumb_font", filename);
+	if (!font) {
+		printf("Info: Can't load font '%s', no preview possible\n", filename);
+		return;
+	}
+
+	/* Would be done via the BLF API, but we're not using a fontid here */
+	font->buf_info.cbuf = buf;
+	font->buf_info.ch = channels;
+	font->buf_info.w = w;
+	font->buf_info.h = h;
+
+	/* Always create the image with a white font,
+	 * the caller can theme how it likes */
+	memcpy(font->buf_info.col, font_color, sizeof(font->buf_info.col));
+	font->pos[1] = (float)h;
+
+	font_size_curr = font_size;
+
+	for (i = 0; i < draw_str_lines; i++) {
+		blf_font_size(font, (unsigned int)MAX2(font_size_min, font_size_curr), dpi);
+
+		/* decrease font size each time */
+		font_size_curr -= (font_size_curr / font_shrink);
+		font_shrink += 1;
+
+		font->pos[1] -= font->glyph_cache->ascender * 1.1f;
+
+		blf_font_buffer(font, draw_str[i]);
+	}
+
+	blf_font_free(font);
+}
diff --git a/source/blender/editors/space_file/file_draw.c b/source/blender/editors/space_file/file_draw.c
index 98c7ddeff77..a6f3a73841e 100644
--- a/source/blender/editors/space_file/file_draw.c
+++ b/source/blender/editors/space_file/file_draw.c
@@ -323,7 +323,7 @@ void file_calc_previews(const bContext *C, ARegion *ar)
 	UI_view2d_totRect_set(v2d, sfile->layout->width, sfile->layout->height);
 }
 
-static void file_draw_preview(uiBlock *block, struct direntry *file, int sx, int sy, ImBuf *imb, FileLayout *layout, bool dropshadow, bool drag)
+static void file_draw_preview(uiBlock *block, struct direntry *file, int sx, int sy, ImBuf *imb, FileLayout *layout, bool is_icon, bool drag)
 {
 	uiBut *but;
 	float fx, fy;
@@ -332,6 +332,7 @@ static void file_draw_preview(uiBlock *block, struct direntry *file, int sx, int
 	float scaledx, scaledy;
 	float scale;
 	int ex, ey;
+	bool use_dropshadow = !is_icon && (file->flags & FILE_TYPE_IMAGE);
 
 	BLI_assert(imb != NULL);
 
@@ -367,17 +368,23 @@ static void file_draw_preview(uiBlock *block, struct direntry *file, int sx, int
 	glBlendFunc(GL_SRC_ALPHA,  GL_ONE_MINUS_SRC_ALPHA);
 
 	/* shadow */
-	if (dropshadow)
+	if (use_dropshadow) {
 		UI_draw_box_shadow(220, (float)xco, (float)yco, (float)(xco + ex), (float)(yco + ey));
+	}
 
 	glEnable(GL_BLEND);
 
 	/* the image */
-	glColor4f(1.0, 1.0, 1.0, 1.0);
+	if (!is_icon && file->flags & FILE_TYPE_FTFONT) {
+		UI_ThemeColor(TH_TEXT);
+	}
+	else {
+		glColor4f(1.0, 1.0, 1.0, 1.0);
+	}
 	glaDrawPixelsTexScaled((float)xco, (float)yco, imb->x, imb->y, GL_RGBA, GL_UNSIGNED_BYTE, GL_NEAREST, imb->rect, scale, scale);
 
 	/* border */
-	if (dropshadow) {
+	if (use_dropshadow) {
 		glColor4f(0.0f, 0.0f, 0.0f, 0.4f);
 		fdrawbox((float)xco, (float)yco, (float)(xco + ex), (float)(yco + ey));
 	}
@@ -549,7 +556,7 @@ void file_draw_list(const bContext *C, ARegion *ar)
 				is_icon = 1;
 			}
 
-			file_draw_preview(block, file, sx, sy, imb, layout, !is_icon && (file->flags & FILE_TYPE_IMAGE), do_drag);
+			file_draw_preview(block, file, sx, sy, imb, layout, is_icon, do_drag);
 		}
 		else {
 			file_draw_icon(block, file->path, sx, sy - (UI_UNIT_Y / 6), get_file_icon(file), ICON_DEFAULT_WIDTH_SCALE, ICON_DEFAULT_HEIGHT_SCALE, do_drag);
diff --git a/source/blender/editors/space_file/filelist.c b/source/blender/editors/space_file/filelist.c
index 66acd7d05e3..5214b611fb9 100644
--- a/source/blender/editors/space_file/filelist.c
+++ b/source/blender/editors/space_file/filelist.c
@@ -1348,6 +1348,9 @@ static void thumbnails_startjob(void *tjv, short *stop, short *do_update, float
 				limg->flags |= FILE_TYPE_MOVIE_ICON;
 			}
 		}
+		else if (limg->flags & FILE_TYPE_FTFONT) {
+			limg->img = IMB_thumb_manage(limg->path, THB_NORMAL, THB_SOURCE_FONT);
+		}
 		*do_update = true;
 		PIL_sleep_ms(10);
 		limg = limg->next;
@@ -1363,7 +1366,7 @@ static void thumbnails_update(void *tjv)
 		while (limg) {
 			if (!limg->done && limg->img) {
 				tj->filelist->filelist[limg->index].image = IMB_dupImBuf(limg->img);
-				/* update flag for movie files where thumbnail can't be created */
+				/* update flag for movie and font files where thumbnail can't be created */
 				if (limg->flags & FILE_TYPE_MOVIE_ICON) {
 					tj->filelist->filelist[limg->index].flags &= ~FILE_TYPE_MOVIE;
 					tj->filelist->filelist[limg->index].flags |= FILE_TYPE_MOVIE_ICON;
@@ -1408,7 +1411,7 @@ void thumbnails_start(FileList *filelist, const bContext *C)
 			continue;
 		}
 		if (!filelist->filelist[idx].image) {
-			if (filelist->filelist[idx].flags & (FILE_TYPE_IMAGE | FILE_TYPE_MOVIE |
+			if (filelist->filelist[idx].flags & (FILE_TYPE_IMAGE | FILE_TYPE_MOVIE | FILE_TYPE_FTFONT |
 			                                     FILE_TYPE_BLENDER | FILE_TYPE_BLENDER_BACKUP))
 			{
 				FileImage *limg = MEM_callocN(sizeof(*limg), __func__);
diff --git a/source/blender/imbuf/CMakeLists.txt b/source/blender/imbuf/CMakeLists.txt
index eadedbd5e00..bdd8230a6ff 100644
--- a/source/blender/imbuf/CMakeLists.txt
+++ b/source/blender/imbuf/CMakeLists.txt
@@ -66,6 +66,7 @@ set(SRC
 	intern/targa.c
 	intern/thumbs.c
 	intern/thumbs_blend.c
+	intern/thumbs_font.c
 	intern/util.c
 	intern/writeimage.c
 
diff --git a/source/blender/imbuf/IMB_thumbs.h b/source/blender/imbuf/IMB_thumbs.h
index bea531c1442..404052f2e8e 100644
--- a/source/blender/imbuf/IMB_thumbs.h
+++ b/source/blender/imbuf/IMB_thumbs.h
@@ -54,7 +54,8 @@ typedef enum ThumbSize {
 typedef enum ThumbSource {
 	THB_SOURCE_IMAGE,
 	THB_SOURCE_MOVIE,
-	THB_SOURCE_BLEND
+	THB_SOURCE_BLEND,
+	THB_SOURCE_FONT,
 } ThumbSource;
 
 /* don't generate thumbs for images bigger then this (100mb) */
@@ -79,6 +80,11 @@ void IMB_thumb_makedirs(void);
 ImBuf *IMB_thumb_load_blend(const char *path);
 void   IMB_thumb_overlay_blend(unsigned int *thumb, int width, int height, float aspect);
 
+/* special function for previewing fonts */
+ImBuf *IMB_thumb_load_font(
+        const char *filename,
+        unsigned int x, unsigned int y);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */
diff --git a/source/blender/imbuf/intern/thumbs.c b/source/blender/imbuf/intern/thumbs.c
index e88cbef206a..78f47b7bc34 100644
--- a/source/blender/imbuf/intern/thumbs.c
+++ b/source/blender/imbuf/intern/thumbs.c
@@ -330,15 +330,22 @@ ImBuf *IMB_thumb_create(const char *path, ThumbSize size, ThumbSource source, Im
 			if (!img) return NULL;
 		}
 		else {
-			if (THB_SOURCE_IMAGE == source || THB_SOURCE_BLEND == source) {
+			if (ELEM(source, THB_SOURCE_IMAGE, THB_SOURCE_BLEND, THB_SOURCE_FONT)) {
 				
 				/* only load if we didnt give an image */
 				if (img == NULL) {
-					if (THB_SOURCE_BLEND == source) {
-						img = IMB_thumb_load_blend(path);
-					}
-					else {
-						img = IMB_loadiffname(path, IB_rect | IB_metadata | IB_thumbnail, NULL);
+					switch (source) {
+						case THB_SOURCE_IMAGE:
+							img = IMB_loadiffname(path, IB_rect | IB_metadata, NULL);
+							break;
+						case THB_SOURCE_BLEND:
+							img = IMB_thumb_load_blend(path);
+							break;
+						case THB_SOURCE_FONT:
+							img = IMB_thumb_load_font(path, tsize, tsize);
+							break;
+						default:
+							BLI_assert(0); /* This should never happen */
 					}
 				}
 
diff --git a/source/blender/imbuf/intern/thumbs_font.c b/source/blender/imbuf/intern/thumbs_font.c
new file mode 100644
index 00000000000..c8982318d80
--- /dev/null
+++ b/source/blender/imbuf/intern/thumbs_font.c
@@ -0,0 +1,73 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Thomas Beck.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/imbuf/intern/thumbs_font.c
+ *  \ingroup imbuf
+ */
+
+#include "BLI_utildefines.h"
+
+#include "IMB_imbuf_types.h"
+#include "IMB_imbuf.h"
+
+#include "IMB_thumbs.h"
+
+
+/* XXX, bad level call */
+#include "../../blenfont/BLF_api.h"
+
+
+struct ImBuf *IMB_thumb_load_font(const char *filename, unsigned int x, unsigned int y)
+{
+	const int font_size = y / 4;
+	const char *thumb_str[] = {
+	    "AaBbCc",
+
+	    "The quick",
+	    "brown fox",
+	    "jumps over",
+	    "the lazy dog",
+	};
+
+	struct ImBuf *ibuf;
+	float font_color[4];
+
+	/* create a white image (theme color is used for drawing) */
+	font_color[0] = font_color[1] = font_color[2] = 1.0f;
+
+	/* fill with zero alpha */
+	font_color[3] = 0.0f;
+
+	ibuf = IMB_allocImBuf(x, y, 32, IB_rect | IB_metadata);
+	IMB_rectfill(ibuf, font_color);
+
+	/* draw with full alpha */
+	font_color[3] = 1.0f;
+
+	BLF_thumb_preview(
+	        filename, thumb_str, ARRAY_SIZE(thumb_str),
+	        font_color, font_size,
+	        (unsigned char *)ibuf->rect, ibuf->x, ibuf->y, ibuf->channels);
+
+	return ibuf;
+}
+