lavc: add a librsvg rasterization library wrapper

Enables rendering of SVG images. This is possible since SVG images
still contain and specify the dimensions in pixels to which they've
been drawn to and thus enable browsers to display them without any
external data. Users can still override and generate images with
arbitrary resolutions.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

1 files changed, 127 insertions, 0 deletions

diff --git a/libavcodec/librsvgdec.c b/libavcodec/librsvgdec.c
new file mode 100644
index 0000000000..29b771c5a3
--- /dev/null
+++ b/libavcodec/librsvgdec.c
@@ -0,0 +1,127 @@
+/*
+ * Librsvg rasterization wrapper
+ * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avcodec.h"
+#include "internal.h"
+#include "libavutil/opt.h"
+#include "librsvg-2.0/librsvg/rsvg.h"
+
+typedef struct LibRSVGContext {
+    AVClass *class;
+
+    int width;
+    int height;
+    int keep_ar;
+} LibRSVGContext;
+
+static int librsvg_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *pkt)
+{
+    int ret;
+    LibRSVGContext *s = avctx->priv_data;
+    AVFrame *frame = data;
+
+    RsvgHandle *handle;
+    RsvgDimensionData unscaled_dimensions, dimensions;
+    cairo_surface_t *image;
+    cairo_t *crender = NULL;
+    GError *error = NULL;
+
+    *got_frame = 0;
+
+    handle = rsvg_handle_new_from_data(pkt->data, pkt->size, &error);
+    if (error) {
+        av_log(avctx, AV_LOG_ERROR, "Error parsing svg!\n");
+        g_error_free(error);
+        return AVERROR_INVALIDDATA;
+    }
+
+    rsvg_handle_get_dimensions(handle, &dimensions);
+    rsvg_handle_get_dimensions(handle, &unscaled_dimensions);
+    dimensions.width  = s->width  ? s->width  : dimensions.width;
+    dimensions.height = s->height ? s->height : dimensions.height;
+    if (s->keep_ar && (s->width || s->height)) {
+        double default_ar = unscaled_dimensions.width/(double)unscaled_dimensions.height;
+        if (!s->width)
+            dimensions.width  = lrintf(dimensions.height * default_ar);
+        else
+            dimensions.height = lrintf(dimensions.width  / default_ar);
+    }
+
+    if ((ret = ff_set_dimensions(avctx, dimensions.width, dimensions.height)))
+        return ret;
+    avctx->pix_fmt = AV_PIX_FMT_BGRA;
+
+    if ((ret = ff_get_buffer(avctx, frame, 0)))
+        return ret;
+    frame->pict_type = AV_PICTURE_TYPE_I;
+    frame->key_frame = 1;
+
+    image = cairo_image_surface_create_for_data(frame->data[0], CAIRO_FORMAT_ARGB32,
+                                                frame->width, frame->height,
+                                                frame->linesize[0]);
+    if (cairo_surface_status(image) != CAIRO_STATUS_SUCCESS)
+        return AVERROR_INVALIDDATA;
+
+    crender = cairo_create(image);
+
+    cairo_set_source_rgba(crender, 0.0, 0.0, 0.0, 1.0f);
+    cairo_paint_with_alpha(crender, 0.0f);
+
+    cairo_scale(crender, dimensions.width / (double)unscaled_dimensions.width,
+                dimensions.height / (double)unscaled_dimensions.height);
+
+    rsvg_handle_render_cairo(handle, crender);
+
+    cairo_destroy(crender);
+    cairo_surface_destroy(image);
+    g_object_unref(handle);
+
+    *got_frame = 1;
+
+    return 0;
+}
+
+#define OFFSET(x) offsetof(LibRSVGContext, x)
+#define DEC (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM)
+static const AVOption options[] = {
+    { "width", "Width to render to (0 for default)", OFFSET(width), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
+    { "height", "Height to render to (0 for default)", OFFSET(height), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
+    { "keep_ar", "Keep aspect ratio with custom width/height", OFFSET(keep_ar), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, DEC },
+    { NULL },
+};
+
+static const AVClass librsvg_decoder_class = {
+    .class_name = "Librsvg",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_librsvg_decoder = {
+    .name           = "librsvg",
+    .long_name      = NULL_IF_CONFIG_SMALL("Librsvg rasterizer"),
+    .priv_class     = &librsvg_decoder_class,
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_SVG,
+    .decode         = librsvg_decode_frame,
+    .priv_data_size = sizeof(LibRSVGContext),
+    .capabilities   = AV_CODEC_CAP_LOSSLESS | AV_CODEC_CAP_DR1,
+};