1 #ifndef _MOVIT_RESAMPLE_EFFECT_H
2 #define _MOVIT_RESAMPLE_EFFECT_H 1
4 // High-quality image resizing, either up or down.
6 // The default scaling offered by the GPU (and as used in ResizeEffect)
7 // is bilinear (optionally mipmapped), which is not the highest-quality
8 // choice, especially for upscaling. ResampleEffect offers the three-lobed
9 // Lanczos kernel, which is among the most popular choices in image
10 // processing. While it does have its weaknesses, in particular a certain
11 // ringing/sharpening effect with artifacts that accumulate over several
12 // consecutive resizings, it is generally regarded as the best tradeoff.
14 // Works in two passes; first horizontal, then vertical (ResampleEffect,
15 // which is what the user is intended to use, instantiates two copies of
16 // SingleResamplePassEffect behind the scenes).
31 class SingleResamplePassEffect;
33 // Public so that it can be benchmarked externally.
39 struct ScalingWeights {
40 unsigned src_bilinear_samples;
41 unsigned dst_samples, num_loops;
43 // Exactly one of these is set.
44 std::unique_ptr<Tap<fp16_int_t>[]> bilinear_weights_fp16;
45 std::unique_ptr<Tap<float>[]> bilinear_weights_fp32;
47 ScalingWeights calculate_scaling_weights(unsigned src_size, unsigned dst_size, float zoom, float offset);
49 class ResampleEffect : public Effect {
54 virtual std::string effect_type_id() const { return "ResampleEffect"; }
56 // We want this for the same reason as ResizeEffect; we could end up scaling
58 virtual bool needs_texture_bounce() const { return true; }
59 virtual bool needs_srgb_primaries() const { return false; }
61 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
63 virtual std::string output_fragment_shader() {
66 virtual void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) {
70 virtual void rewrite_graph(EffectChain *graph, Node *self);
71 virtual bool set_float(const std::string &key, float value);
75 void update_offset_and_zoom();
77 // Both of these are owned by us if owns_effects is true (before finalize()),
78 // and otherwise owned by the EffectChain.
80 SingleResamplePassEffect *hpass, *vpass;
81 int input_width, input_height, output_width, output_height;
83 float offset_x, offset_y;
85 float zoom_center_x, zoom_center_y;
89 class SingleResamplePassEffect : public Effect {
91 // If parent is non-nullptr, calls to inform_input_size will be forwarded,
92 // so that it can inform both passes about the right input and output
94 SingleResamplePassEffect(ResampleEffect *parent);
95 ~SingleResamplePassEffect();
96 virtual std::string effect_type_id() const { return "SingleResamplePassEffect"; }
98 std::string output_fragment_shader();
100 virtual bool needs_texture_bounce() const { return true; }
101 virtual bool needs_srgb_primaries() const { return false; }
102 virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
104 virtual void inform_added(EffectChain *chain) { this->chain = chain; }
105 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {
106 if (parent != nullptr) {
107 parent->inform_input_size(input_num, width, height);
110 virtual bool changes_output_size() const { return true; }
111 virtual bool sets_virtual_output_size() const { return false; }
113 virtual void get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const {
114 *virtual_width = *width = this->output_width;
115 *virtual_height = *height = this->output_height;
118 void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
120 enum Direction { HORIZONTAL = 0, VERTICAL = 1 };
123 void update_texture(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
125 ResampleEffect *parent;
129 GLint uniform_sample_tex;
130 float uniform_num_loops, uniform_slice_height, uniform_sample_x_scale, uniform_sample_x_offset;
131 float uniform_whole_pixel_offset;
132 int uniform_num_samples;
134 int input_width, input_height, output_width, output_height;
137 int last_input_width, last_input_height, last_output_width, last_output_height;
138 float last_offset, last_zoom;
139 int src_bilinear_samples, num_loops;
141 int last_texture_width, last_texture_height;
142 GLuint last_texture_internal_format;
147 #endif // !defined(_MOVIT_RESAMPLE_EFFECT_H)