Merge pull request #2195 from libvips/text-colour-rendering

Text colour rendering

.github/workflows/ci.yml

@@ -60,7 +60,8 @@ jobs:
 
       - name: Install macOS dependencies
         if: contains(matrix.os, 'macos')
-        run:
+        run: |
+          brew update 
           brew install
             autoconf automake libtool
             gtk-doc gobject-introspection

ChangeLog

@@ -22,6 +22,7 @@
 - add vips_image_[set|get]_array_double()
 - add GIF load with libnsgif
 - add JPEG2000 load and save
+- add "rgba" flag to vips_text() to enable full colour text rendering
 
 22/12/20 start 8.10.6
 - don't seek on bad file descriptors [kleisauke]

README.md

@@ -243,10 +243,10 @@ If you are going to be using libvips with untrusted images, perhaps in a
 web server, for example, you should consider the security implications of
 enabling a package with such a large attack surface. 
 
-### pangoft2
+### pangocairo
 
 If available, libvips adds support for text rendering. You need the
-package pangoft2 in `pkg-config --list-all`.
+package pangocairo in `pkg-config --list-all`.
 
 ### orc-0.4
 

configure.ac

@@ -1083,25 +1083,25 @@ fi
 VIPS_CFLAGS="$VIPS_CFLAGS $LIBWEBP_CFLAGS"
 VIPS_LIBS="$VIPS_LIBS $LIBWEBP_LIBS"
 
-# pangoft2
+# pangocairo for text rendering
-AC_ARG_WITH([pangoft2], 
+AC_ARG_WITH([pangocairo], 
-  AS_HELP_STRING([--without-pangoft2], 
+  AS_HELP_STRING([--without-pangocairo], 
-    [build without pangoft2 (default: test)]))
+    [build without pangocairo (default: test)]))
 
-if test x"$with_pangoft2" != x"no"; then
+if test x"$with_pangocairo" != x"no"; then
-  PKG_CHECK_MODULES(PANGOFT2, pangoft2,
+  PKG_CHECK_MODULES(PANGOCAIRO, pangocairo,
-    [AC_DEFINE(HAVE_PANGOFT2,1,[define if you have pangoft2 installed.])
+    [AC_DEFINE(HAVE_PANGOCAIRO,1,[define if you have pangocairo installed.])
-     with_pangoft2=yes
+     with_pangocairo=yes
-     PACKAGES_USED="$PACKAGES_USED pangoft2"
+     PACKAGES_USED="$PACKAGES_USED pangocairo"
     ],
-    [AC_MSG_WARN([pangoft2 not found; disabling pangoft2 support])
+    [AC_MSG_WARN([pangocairo not found; disabling pangocairo support])
-     with_pangoft2=no
+     with_pangocairo=no
     ]
   )
 fi
 
-VIPS_CFLAGS="$VIPS_CFLAGS $PANGOFT2_CFLAGS"
+VIPS_CFLAGS="$VIPS_CFLAGS $PANGOCAIRO_CFLAGS"
-VIPS_LIBS="$VIPS_LIBS $PANGOFT2_LIBS"
+VIPS_LIBS="$VIPS_LIBS $PANGOCAIRO_LIBS"
 
 # look for TIFF with pkg-config ... fall back to our tester
 # pkgconfig support for libtiff starts with libtiff-4
@@ -1325,7 +1325,7 @@ use fftw3 for FFT: $with_fftw, \
 accelerate loops with orc: $with_orc, \
 ICC profile support with lcms: $with_lcms, \
 zlib: $with_zlib, \
-text rendering with pangoft2: $with_pangoft2, \
+text rendering with pangocairo: $with_pangocairo, \
 EXIF metadata support with libexif: $with_libexif, \
 JPEG load/save with libjpeg: $with_jpeg, \
 PNG load with libspng: $with_libspng, \
@@ -1427,7 +1427,7 @@ accelerate loops with orc:              $with_orc
  (requires orc-0.4.11 or later)
 ICC profile support with lcms:          $with_lcms
 zlib:                                   $with_zlib
-text rendering with pangoft2:           $with_pangoft2
+text rendering with pangocairo:         $with_pangocairo
 EXIF metadata support with libexif:     $with_libexif
 
 ## File format support

libvips/create/create.c

@@ -116,9 +116,9 @@ vips_create_operation_init( void )
 	extern GType vips_gaussmat_get_type( void ); 
 	extern GType vips_logmat_get_type( void ); 
 	extern GType vips_gaussnoise_get_type( void ); 
-#ifdef HAVE_PANGOFT2
+#ifdef HAVE_PANGOCAIRO
 	extern GType vips_text_get_type( void ); 
-#endif /*HAVE_PANGOFT2*/
+#endif /*HAVE_PANGOCAIRO*/
 	extern GType vips_xyz_get_type( void ); 
 	extern GType vips_eye_get_type( void ); 
 	extern GType vips_grey_get_type( void ); 
@@ -146,9 +146,9 @@ vips_create_operation_init( void )
 	vips_gaussmat_get_type();
 	vips_logmat_get_type();
 	vips_gaussnoise_get_type(); 
-#ifdef HAVE_PANGOFT2
+#ifdef HAVE_PANGOCAIRO
 	vips_text_get_type(); 
-#endif /*HAVE_PANGOFT2*/
+#endif /*HAVE_PANGOCAIRO*/
 	vips_xyz_get_type(); 
 	vips_eye_get_type(); 
 	vips_grey_get_type(); 

libvips/create/text.c

@@ -32,6 +32,9 @@
  * 	- fitting could occasionally terminate early [levmorozov]
  * 16/5/20 [keiviv]
  * 	- don't add fontfiles repeatedly
+ * 12/4/21
+ * 	- switch to cairo for text rendering
+ * 	- add rgba flag
  */
 
 /*
@@ -74,11 +77,14 @@
 #include <string.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
 
-#ifdef HAVE_PANGOFT2
+#ifdef HAVE_PANGOCAIRO
 
+#include <cairo.h>
 #include <pango/pango.h>
-#include <pango/pangoft2.h>
+#include <pango/pangocairo.h>
+#include <fontconfig/fontconfig.h>
 
 #include "pcreate.h"
 
@@ -94,8 +100,8 @@ typedef struct _VipsText {
 	gboolean justify;
 	int dpi;
 	char *fontfile;
+	gboolean rgba;
 
-	FT_Bitmap bitmap;
 	PangoContext *context;
 	PangoLayout *layout;
 
@@ -129,7 +135,6 @@ vips_text_dispose( GObject *gobject )
 
 	VIPS_UNREF( text->layout ); 
 	VIPS_UNREF( text->context ); 
-	VIPS_FREE( text->bitmap.buffer ); 
 
 	G_OBJECT_CLASS( vips_text_parent_class )->dispose( gobject );
 }
@@ -186,8 +191,8 @@ vips_text_get_extents( VipsText *text, VipsRect *extents )
 	PangoRectangle ink_rect;
 	PangoRectangle logical_rect;
 
-	pango_ft2_font_map_set_resolution( 
+	pango_cairo_font_map_set_resolution( 
-		PANGO_FT2_FONT_MAP( vips_text_fontmap ), text->dpi, text->dpi );
+		PANGO_CAIRO_FONT_MAP( vips_text_fontmap ), text->dpi );
 
 	VIPS_UNREF( text->layout );
 	if( !(text->layout = text_layout_new( text->context, 
@@ -340,9 +345,12 @@ vips_text_build( VipsObject *object )
 	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
 	VipsCreate *create = VIPS_CREATE( object );
 	VipsText *text = (VipsText *) object;
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 3 );
 
 	VipsRect extents;
-	int y;
+	VipsImage *image;
+	cairo_surface_t *surface;
+	cairo_t *cr;
 
 	if( VIPS_OBJECT_CLASS( vips_text_parent_class )->build( object ) )
 		return( -1 );
@@ -356,7 +364,7 @@ vips_text_build( VipsObject *object )
 	g_mutex_lock( vips_text_lock ); 
 
 	if( !vips_text_fontmap )
-		vips_text_fontmap = pango_ft2_font_map_new();
+		vips_text_fontmap = pango_cairo_font_map_new();
 	if( !vips_text_fontfiles )
 		vips_text_fontfiles = 
 			g_hash_table_new( g_str_hash, g_str_equal );
@@ -399,39 +407,64 @@ vips_text_build( VipsObject *object )
 		return( -1 );
 	}
 
-	text->bitmap.width = extents.width;
+	/* Set DPI as pixels/mm.
-	text->bitmap.pitch = (text->bitmap.width + 3) & ~3;
+	 */
-	text->bitmap.rows = extents.height;
+	image = t[0] = vips_image_new_memory();
-	if( !(text->bitmap.buffer = 
+	vips_image_init_fields( image,
-		VIPS_ARRAY( NULL, 
+		extents.width, extents.height, 4, 
-			text->bitmap.pitch * text->bitmap.rows, VipsPel )) ) {
+		VIPS_FORMAT_UCHAR, VIPS_CODING_NONE, 
+		VIPS_INTERPRETATION_sRGB,
+		text->dpi / 25.4, text->dpi / 25.4 );
+
+	vips_image_pipelinev( image, VIPS_DEMAND_STYLE_ANY, NULL );
+	image->Xoffset = extents.left;
+	image->Yoffset = extents.top;
+
+	if( vips_image_write_prepare( image ) ) {
 		g_mutex_unlock( vips_text_lock ); 
 		return( -1 );
 	}
-	text->bitmap.num_grays = 256;
-	text->bitmap.pixel_mode = ft_pixel_mode_grays;
-	memset( text->bitmap.buffer, 0x00, 
-		text->bitmap.pitch * text->bitmap.rows );
 
-	pango_ft2_render_layout( &text->bitmap, text->layout, 
+	surface = cairo_image_surface_create_for_data( 
-		-extents.left, -extents.top );
+		VIPS_IMAGE_ADDR( image, 0, 0 ), 
+		CAIRO_FORMAT_ARGB32,
+		image->Xsize, image->Ysize,
+		VIPS_IMAGE_SIZEOF_LINE( image ) );
+	cr = cairo_create( surface );
+	cairo_surface_destroy( surface );
+
+	cairo_translate( cr, -extents.left, -extents.top );
+
+	pango_cairo_show_layout( cr, text->layout );
+
+	cairo_destroy( cr );
 
 	g_mutex_unlock( vips_text_lock ); 
 
-	vips_image_init_fields( create->out,
+	if( text->rgba ) {
-		text->bitmap.width, text->bitmap.rows, 1, 
+		int y;
-		VIPS_FORMAT_UCHAR, VIPS_CODING_NONE, 
-		VIPS_INTERPRETATION_MULTIBAND,
-		1.0, 1.0 ); 
-	vips_image_pipelinev( create->out, 
-		VIPS_DEMAND_STYLE_ANY, NULL );
-	create->out->Xoffset = extents.left;
-	create->out->Yoffset = extents.top;
 
-	for( y = 0; y < text->bitmap.rows; y++ ) 
+		/* Cairo makes pre-multipled BRGA -- we must byteswap and 
-		if( vips_image_write_line( create->out, y, 
+		 * unpremultiply.
-			(VipsPel *) text->bitmap.buffer + 
+		 */
-				y * text->bitmap.pitch ) )
+		for( y = 0; y < image->Ysize; y++ ) 
+			vips__premultiplied_bgra2rgba( 
+				(guint32 *) 
+					VIPS_IMAGE_ADDR( image, 0, y ),
+				image->Xsize ); 
+	}
+	else {
+		/* We just want the alpha channel.
+		 */
+		if( vips_extract_band( image, &t[1], 3, NULL ) ||
+			vips_copy( t[1], &t[2], 
+				"interpretation", VIPS_INTERPRETATION_MULTIBAND,
+				NULL ) )
+			return( -1 );
+		image = t[2];
+	}
+
+	if( vips_image_write( image, create->out ) )
 		return( -1 );
 
 	return( 0 );
@@ -534,6 +567,13 @@ vips_text_class_init( VipsTextClass *class )
 		G_STRUCT_OFFSET( VipsText, fontfile ),
 		NULL ); 
 
+	VIPS_ARG_BOOL( class, "rgba", 9, 
+		_( "RGBA" ), 
+		_( "Enable RGBA output" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsText, rgba ),
+		FALSE );
+
 }
 
 static void
@@ -541,11 +581,10 @@ vips_text_init( VipsText *text )
 {
 	text->align = VIPS_ALIGN_LOW;
 	text->dpi = 72;
-	text->bitmap.buffer = NULL;
 	VIPS_SETSTR( text->font, "sans 12" ); 
 }
 
-#endif /*HAVE_PANGOFT2*/
+#endif /*HAVE_PANGOCAIRO*/
 
 /**
  * vips_text:
@@ -563,17 +602,22 @@ vips_text_init( VipsText *text )
  * * @justify: %gboolean, justify lines
  * * @dpi: %gint, render at this resolution
  * * @autofit_dpi: %gint, read out auto-fitted DPI 
+ * * @rgba: %gboolean, enable RGBA output
  * * @spacing: %gint, space lines by this in points
  *
- * Draw the string @text to an image. @out is a one-band 8-bit
+ * Draw the string @text to an image. @out is normally a one-band 8-bit
  * unsigned char image, with 0 for no text and 255 for text. Values between
  * are used for anti-aliasing.
  *
+ * Set @rgba to enable RGBA output. This is useful for colour emoji rendering,
+ * or support for pango markup features like `<span
+ * foreground="red">Red!</span>`.
+ *
  * @text is the text to render as a UTF-8 string. It can contain Pango markup,
- * for example "&lt;i&gt;The&lt;/i&gt;Guardian".
+ * for example `<i>The</i>Guardian`.
  *
  * @font is the font to render with, as a fontconfig name. Examples might be
- * "sans 12" or perhaps "bitstream charter bold 10".
+ * `sans 12` or perhaps `bitstream charter bold 10`.
  *
  * You can specify a font to load with @fontfile. You'll need to also set the
  * name of the font with @font.