Fix alpha blending with with offset; should help with #1155.

[dcpomatic.git] / src / lib / image.cc

diff --git a/src/lib/image.cc b/src/lib/image.cc
index a6354f2d16793c8790930f7eb4f622bbfd1db7d0..b85451fb32f11ef4101363f27544eba9961c04e4 100644 (file)
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -220,6 +220,12 @@ Image::crop_scale_window (
        return out;
 }
 
+shared_ptr<Image>
+Image::convert_pixel_format (dcp::YUVToRGB yuv_to_rgb, AVPixelFormat out_format, bool out_aligned, bool fast) const
+{
+       return scale(size(), yuv_to_rgb, out_format, out_aligned, fast);
+}
+
 /** @param out_size Size to scale to.
  *  @param yuv_to_rgb YUVToRGB transform transform to use, if required.
  *  @param out_format Output pixel format.
@@ -430,36 +436,6 @@ Image::make_transparent ()
        memset (data()[0], 0, sample_size(0).height * stride()[0]);
 }
 
-template <class T>
-void
-component (
-       int n,
-       Image* base,
-       shared_ptr<const Image> other,
-       shared_ptr<const Image> rgba,
-       int start_base_x, int start_base_y,
-       int start_other_x, int start_other_y
-       )
-{
-       dcp::Size const base_size = base->sample_size(n);
-       dcp::Size const other_size = other->sample_size(n);
-       for (int by = start_base_y, oy = start_other_y; by < base_size.height && oy < other_size.height; ++by, ++oy) {
-               /* base image */
-               T* bp = ((T*) (base->data()[n] + by * base->stride()[n])) + start_base_x;
-               /* overlay image */
-               T* op = ((T*) (other->data()[n] + oy * other->stride()[n]));
-               /* original RGBA for alpha channel */
-               uint8_t* rp = rgba->data()[0] + oy * rgba->stride()[0];
-               for (int bx = start_base_x, ox = start_other_x; bx < base_size.width && ox < other_size.width; ++bx, ++ox) {
-                       float const alpha = float (rp[3]) / 255;
-                       *bp = *op * alpha + *bp * (1 - alpha);
-                       ++bp;
-                       ++op;
-                       rp += 4;
-               }
-       }
-}
-
 void
 Image::alpha_blend (shared_ptr<const Image> other, Position<int> position)
 {
@@ -579,19 +555,67 @@ Image::alpha_blend (shared_ptr<const Image> other, Position<int> position)
        }
        case AV_PIX_FMT_YUV420P:
        {
-               shared_ptr<Image> yuv = other->scale (other->size(), dcp::YUV_TO_RGB_REC709, _pixel_format, false, false);
-               component<uint8_t> (0, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
-               component<uint8_t> (1, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
-               component<uint8_t> (2, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
+               shared_ptr<Image> yuv = other->convert_pixel_format (dcp::YUV_TO_RGB_REC709, _pixel_format, false, false);
+               dcp::Size const ts = size();
+               dcp::Size const os = yuv->size();
+               for (int ty = start_ty, oy = start_oy; ty < ts.height && oy < os.height; ++ty, ++oy) {
+                       int const hty = ty / 2;
+                       int const hoy = oy / 2;
+                       uint8_t* tY = data()[0] + (ty * stride()[0]) + start_tx;
+                       uint8_t* tU = data()[1] + (hty * stride()[1]) + start_tx / 2;
+                       uint8_t* tV = data()[2] + (hty * stride()[2]) + start_tx / 2;
+                       uint8_t* oY = yuv->data()[0] + (oy * yuv->stride()[0]) + start_ox;
+                       uint8_t* oU = yuv->data()[1] + (hoy * yuv->stride()[1]) + start_ox / 2;
+                       uint8_t* oV = yuv->data()[2] + (hoy * yuv->stride()[2]) + start_ox / 2;
+                       uint8_t* alpha = other->data()[0] + (oy * other->stride()[0]) + start_ox * 4;
+                       for (int tx = start_tx, ox = start_ox; tx < ts.width && ox < os.width; ++tx, ++ox) {
+                               float const a = float(alpha[3]) / 255;
+                               *tY = *oY * a + *tY * (1 - a);
+                               *tU = *oU * a + *tU * (1 - a);
+                               *tV = *oV * a + *tV * (1 - a);
+                               ++tY;
+                               ++oY;
+                               if (tx % 2) {
+                                       ++tU;
+                                       ++tV;
+                               }
+                               if (ox % 2) {
+                                       ++oU;
+                                       ++oV;
+                               }
+                               alpha += 4;
+                       }
+               }
                break;
        }
        case AV_PIX_FMT_YUV420P10:
        case AV_PIX_FMT_YUV422P10LE:
        {
-               shared_ptr<Image> yuv = other->scale (other->size(), dcp::YUV_TO_RGB_REC709, _pixel_format, false, false);
-               component<uint16_t> (0, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
-               component<uint8_t>  (1, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
-               component<uint8_t>  (2, this, yuv, other, start_tx, start_ty, start_ox, start_oy);
+               shared_ptr<Image> yuv = other->convert_pixel_format (dcp::YUV_TO_RGB_REC709, _pixel_format, false, false);
+               dcp::Size const ts = size();
+               dcp::Size const os = yuv->size();
+               for (int ty = start_ty, oy = start_oy; ty < ts.height && oy < os.height; ++ty, ++oy) {
+                       uint16_t* tY = (uint16_t *) (data()[0] + (ty * stride()[0])) + start_tx;
+                       uint8_t* tU = data()[1] + (ty * stride()[1]) + start_tx;
+                       uint8_t* tV = data()[2] + (ty * stride()[2]) + start_tx;
+                       uint16_t* oY = (uint16_t *) (yuv->data()[0] + (oy * yuv->stride()[0])) + start_ox;
+                       uint8_t* oU = yuv->data()[1] + (oy * yuv->stride()[1]) + start_ox;
+                       uint8_t* oV = yuv->data()[2] + (oy * yuv->stride()[2]) + start_ox;
+                       uint8_t* alpha = other->data()[0] + (oy * other->stride()[0]) + start_ox * 4;
+                       for (int tx = start_tx, ox = start_ox; tx < ts.width && ox < os.width; ++tx, ++ox) {
+                               float const a = float(alpha[3]) / 255;
+                               *tY = *oY * a + *tY * (1 - a);
+                               *tU = *oU * a + *tU * (1 - a);
+                               *tV = *oV * a + *tV * (1 - a);
+                               ++tY;
+                               ++tU;
+                               ++tV;
+                               ++oY;
+                               ++oU;
+                               ++oV;
+                               alpha += 4;
+                       }
+               }
                break;
        }
        default: