In the README, document that we have luma mix.

[movit] / padding_effect.cpp

diff --git a/padding_effect.cpp b/padding_effect.cpp
index 2e428c4556d25bbec390fca0ad9a220e7362b86e..a70025d015475f885a9841d96e40c08fe3ac762e 100644 (file)
--- a/padding_effect.cpp
+++ b/padding_effect.cpp
@@ -1,36 +1,46 @@
-#include <math.h>
 #include <GL/glew.h>
+#include <assert.h>
 
+#include "effect_util.h"
 #include "padding_effect.h"
 #include "util.h"
 
+using namespace std;
+
+namespace movit {
+
 PaddingEffect::PaddingEffect()
        : border_color(0.0f, 0.0f, 0.0f, 0.0f),
          output_width(1280),
          output_height(720),
          top(0),
-         left(0)
+         left(0),
+         pad_from_bottom(0)
 {
        register_vec4("border_color", (float *)&border_color);
        register_int("width", &output_width);
        register_int("height", &output_height);
        register_float("top", &top);
        register_float("left", &left);
+       register_int("pad_from_bottom", &pad_from_bottom);
 }
 
-std::string PaddingEffect::output_fragment_shader()
+string PaddingEffect::output_fragment_shader()
 {
        return read_file("padding_effect.frag");
 }
 
-void PaddingEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void PaddingEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
 {
        Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
 
-       float offset[2] = {
-               left / output_width,
-               (output_height - input_height - top) / output_height
-       };
+       float offset[2];
+       offset[0] = left / output_width;
+       if (pad_from_bottom) {
+               offset[1] = top / output_height;
+       } else {
+               offset[1] = (output_height - input_height - top) / output_height;
+       }
        set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
 
        float scale[2] = {
@@ -63,12 +73,16 @@ void PaddingEffect::set_gl_state(GLuint glsl_program_num, const std::string &pre
 // differently in different modes.
 
 // 0.0 and 1.0 are interpreted the same, no matter the gamma ramp.
-// Alpha is not affected by gamma.
+// Alpha is not affected by gamma per se, but the combination of
+// premultiplied alpha and non-linear gamma curve does not make sense,
+// so if could possibly be converting blank alpha to non-blank
+// (ie., premultiplied), we need our output to be in linear light.
 bool PaddingEffect::needs_linear_light() const
 {
        if ((border_color.r == 0.0 || border_color.r == 1.0) &&
            (border_color.g == 0.0 || border_color.g == 1.0) &&
-           (border_color.b == 0.0 || border_color.b == 1.0)) {
+           (border_color.b == 0.0 || border_color.b == 1.0) &&
+           border_color.a == 1.0) {
                return false;
        }
        return true;
@@ -89,20 +103,32 @@ bool PaddingEffect::needs_srgb_primaries() const
        return true;
 }
 
-// If the border color is black, it doesn't matter if we're pre- or postmultiplied
-// (or even blank, as a hack). Otherwise, it does.
 Effect::AlphaHandling PaddingEffect::alpha_handling() const
 {
-       if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
+       // If the border color is black, it doesn't matter if we're pre- or postmultiplied.
+       // Note that for non-solid black (i.e. alpha < 1.0), we're equally fine with
+       // pre- and postmultiplied, but later effects might change this status
+       // (consider e.g. blur), so setting DONT_CARE_ALPHA_TYPE is inappropriate,
+       // as it propagate blank alpha through this effect.
+       if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0 && border_color.a == 1.0) {
                return DONT_CARE_ALPHA_TYPE;
        }
-       return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED;
+
+       // If the border color is solid, we preserve blank alpha, as we never output any
+       // new non-solid pixels.
+       if (border_color.a == 1.0) {
+               return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK;
+       }
+
+       // Otherwise, we're going to output our border color in premultiplied alpha,
+       // so the other pixels better be premultiplied as well.
+       return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA;
 }
        
-void PaddingEffect::get_output_size(unsigned *width, unsigned *height) const
+void PaddingEffect::get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const
 {
-       *width = output_width;
-       *height = output_height;
+       *virtual_width = *width = output_width;
+       *virtual_height = *height = output_height;
 }
        
 void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
@@ -111,3 +137,5 @@ void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsign
        input_width = width;
        input_height = height;
 }
+
+}  // namespace movit