4 #include "effect_util.h"
5 #include "padding_effect.h"
12 PaddingEffect::PaddingEffect()
13 : border_color(0.0f, 0.0f, 0.0f, 0.0f),
19 register_vec4("border_color", (float *)&border_color);
20 register_int("width", &output_width);
21 register_int("height", &output_height);
22 register_float("top", &top);
23 register_float("left", &left);
26 string PaddingEffect::output_fragment_shader()
28 return read_file("padding_effect.frag");
31 void PaddingEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
33 Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
37 (output_height - input_height - top) / output_height
39 set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
42 float(output_width) / input_width,
43 float(output_height) / input_height
45 set_uniform_vec2(glsl_program_num, prefix, "scale", scale);
47 // Due to roundoff errors, the test against 0.5 is seldom exact,
48 // even though we test for less than and not less-than-or-equal.
49 // We'd rather keep an extra border pixel in those very rare cases
50 // (where the image is shifted pretty much exactly a half-pixel)
51 // than losing a pixel in the common cases of integer shift.
52 // Thus the 1e-3 fudge factors.
53 float texcoord_min[2] = {
54 float((0.5f - 1e-3) / input_width),
55 float((0.5f - 1e-3) / input_height)
57 set_uniform_vec2(glsl_program_num, prefix, "texcoord_min", texcoord_min);
59 float texcoord_max[2] = {
60 float(1.0f - (0.5f - 1e-3) / input_width),
61 float(1.0f - (0.5f - 1e-3) / input_height)
63 set_uniform_vec2(glsl_program_num, prefix, "texcoord_max", texcoord_max);
66 // We don't change the pixels of the image itself, so the only thing that
67 // can make us less flexible is if the border color can be interpreted
68 // differently in different modes.
70 // 0.0 and 1.0 are interpreted the same, no matter the gamma ramp.
71 // Alpha is not affected by gamma per se, but the combination of
72 // premultiplied alpha and non-linear gamma curve does not make sense,
73 // so if could possibly be converting blank alpha to non-blank
74 // (ie., premultiplied), we need our output to be in linear light.
75 bool PaddingEffect::needs_linear_light() const
77 if ((border_color.r == 0.0 || border_color.r == 1.0) &&
78 (border_color.g == 0.0 || border_color.g == 1.0) &&
79 (border_color.b == 0.0 || border_color.b == 1.0) &&
80 border_color.a == 1.0) {
86 // The white point is the same (D65) in all the color spaces we currently support,
87 // so any gray would be okay, but we don't really have a guarantee for that.
88 // Stay safe and say that only pure black and pure white is okay.
89 // Alpha is not affected by color space.
90 bool PaddingEffect::needs_srgb_primaries() const
92 if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
95 if (border_color.r == 1.0 && border_color.g == 1.0 && border_color.b == 1.0) {
101 Effect::AlphaHandling PaddingEffect::alpha_handling() const
103 // If the border color is black, it doesn't matter if we're pre- or postmultiplied.
104 // Note that for non-solid black (i.e. alpha < 1.0), we're equally fine with
105 // pre- and postmultiplied, but later effects might change this status
106 // (consider e.g. blur), so setting DONT_CARE_ALPHA_TYPE is inappropriate,
107 // as it propagate blank alpha through this effect.
108 if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0 && border_color.a == 1.0) {
109 return DONT_CARE_ALPHA_TYPE;
112 // If the border color is solid, we preserve blank alpha, as we never output any
113 // new non-solid pixels.
114 if (border_color.a == 1.0) {
115 return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK;
118 // Otherwise, we're going to output our border color in premultiplied alpha,
119 // so the other pixels better be premultiplied as well.
120 return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA;
123 void PaddingEffect::get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const
125 *virtual_width = *width = output_width;
126 *virtual_height = *height = output_height;
129 void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
131 assert(input_num == 0);
133 input_height = height;