Add nearest and bicubic filtering

imagescrollareagl.cpp

@@ -14,6 +14,8 @@
 #include <cmath>
 #include <QElapsedTimer>
 
+int FILTERING = 1;
+
 struct RawImageType
 {
     QOpenGLTexture::PixelFormat pixelFormat;
@@ -375,6 +377,8 @@ void ImageWidget::paintGL()
         m_program->setUniformValue("bw", m_bwImg && !m_superpixel);
         m_program->setUniformValue("false_color", m_falseColor && m_bwImg);
         m_program->setUniformValue("invert", m_invert);
+        m_program->setUniformValue("filtering", m_scale > 1.0f ? FILTERING : 1);
+        qDebug() << 1.0 / m_scale;
 #ifdef COLOR_MANAGMENT
         m_program->setUniformValue("srgb", m_srgb);
 #endif

settingsdialog.cpp

@@ -8,6 +8,7 @@
 
 extern int DEFAULT_WIDTH;
 extern double SATURATION;
+extern int FILTERING;
 
 class EvenNumber : public QSpinBox
 {
@@ -59,10 +60,15 @@ SettingsDialog::SettingsDialog(QWidget *parent) : QDialog(parent)
     m_useNativeDialog = new QCheckBox(tr("Don't use native file dialog"), this);
     m_useNativeDialog->setChecked(QApplication::testAttribute(Qt::AA_DontUseNativeDialogs));
 
+    m_filtering = new QComboBox(this);
+    m_filtering->addItems({tr("Nearest"), tr("Bilinear"), tr("Bicubic")});
+    m_filtering->setCurrentIndex(FILTERING);
+
     layout->addRow(tr("Image preload count"), m_preloadImages);
     layout->addRow(tr("Thumbnails size"), m_thumSize);
     layout->addRow(tr("Saturation"), m_saturation);
     layout->addRow(m_useNativeDialog);
+    layout->addRow(tr("Image filtering"), m_filtering);
     //layout->addRow(new QLabel(tr("Changes in settings will take effect after program restart.")));
 
     QDialogButtonBox *buttonBox = new QDialogButtonBox(this);
@@ -82,6 +88,7 @@ void SettingsDialog::loadSettings()
     THUMB_SIZE_BORDER_Y = THUMB_SIZE + 30;
     DEFAULT_WIDTH = settings.value("settings/preloadimagecount", DEFAULT_WIDTH).toInt();
     SATURATION = settings.value("settings/saturation", 95.0).toDouble() / 100.0;
+    FILTERING = settings.value("settings/filtering", FILTERING).toInt();
     QApplication::setAttribute(Qt::AA_DontUseNativeDialogs, settings.value("settings/dontusenativedialogs", false).toBool());
 }
 
@@ -102,6 +109,8 @@ void SettingsDialog::saveSettings()
     settings.setValue("settings/preloadimagecount", m_preloadImages->value());
     settings.setValue("settings/dontusenativedialogs", m_useNativeDialog->isChecked());
     settings.setValue("settings/saturation", m_saturation->value());
+    FILTERING = m_filtering->currentIndex();
+    settings.setValue("settings/filtering", FILTERING);
     SATURATION = m_saturation->value() / 100.0;
     QApplication::setAttribute(Qt::AA_DontUseNativeDialogs, m_useNativeDialog->isChecked());
     if(DEFAULT_WIDTH != m_preloadImages->value())

settingsdialog.h

@@ -4,6 +4,7 @@
 #include <QDialog>
 #include <QSpinBox>
 #include <QCheckBox>
+#include <QComboBox>
 
 class SettingsDialog : public QDialog
 {
@@ -21,6 +22,7 @@ private:
     QSpinBox *m_thumSize;
     QDoubleSpinBox *m_saturation;
     QCheckBox *m_useNativeDialog;
+    QComboBox *m_filtering;
 };
 
 #endif // SETTINGSDIALOG_H

shaders/image.frag

@@ -7,6 +7,7 @@ uniform bool bw;
 uniform bool invert;
 uniform bool srgb;
 uniform bool false_color;
+uniform int filtering;
 in vec2 qt_TexCoord0;
 layout(location = 0) out vec4 color;
 
@@ -35,7 +36,8 @@ vec3 falsecolor(float color)
             vec3(1.0, 0.0, 0.0), vec3(1.0, 0.0, 0.0));//red
     color *= 5.0;
     int i = int(color);
-    return mix(pallete[i], pallete[i+1], fract(color));
+    float f = fract(color);
+    return mix(pallete[i], pallete[i+1], f);// * (f * 0.5 + 0.5);
 }
 
 vec3 checker()
@@ -44,9 +46,104 @@ vec3 checker()
     return vec3(step(pattern.x * pattern.y, 0.0) * 0.25 + 0.25);
 }
 
+vec4 cubic(float v)
+{
+    vec4 n = vec4(1.0, 2.0, 3.0, 4.0) - v;
+    vec4 s = n * n * n;
+    float x = s.x;
+    float y = s.y - 4.0 * s.x;
+    float z = s.z - 4.0 * s.y + 6.0 * s.x;
+    float w = 6.0 - x - y - z;
+    return vec4(x, y, z, w) * (1.0/6.0);
+}
+
+vec4 textureBicubic(sampler2D sampler, vec2 texCoords)
+{
+    vec2 texSize = textureSize(sampler, 0);
+    vec2 invTexSize = 1.0 / texSize;
+
+    texCoords = texCoords * texSize - 0.5;
+
+    vec2 fxy = fract(texCoords);
+    texCoords -= fxy;
+
+    vec4 xcubic = cubic(fxy.x);
+    vec4 ycubic = cubic(fxy.y);
+
+    vec4 c = texCoords.xxyy + vec2 (-0.5, +1.5).xyxy;
+
+    vec4 s = vec4(xcubic.xz + xcubic.yw, ycubic.xz + ycubic.yw);
+    vec4 offset = c + vec4 (xcubic.yw, ycubic.yw) / s;
+
+    offset *= invTexSize.xxyy;
+
+    vec4 sample0 = texture(sampler, offset.xz);
+    vec4 sample1 = texture(sampler, offset.yz);
+    vec4 sample2 = texture(sampler, offset.xw);
+    vec4 sample3 = texture(sampler, offset.yw);
+
+    float sx = s.x / (s.x + s.y);
+    float sy = s.z / (s.z + s.w);
+
+    return mix(mix(sample3, sample2, sx), mix(sample1, sample0, sx), sy);
+}
+
+vec4 textureCatmul(sampler2D sampler, vec2 texCoords)
+{
+   ivec2 texSize = textureSize(sampler, 0);
+
+   texCoords = texCoords * vec2(texSize) - 0.5;
+
+   ivec2 texel = ivec2(floor(texCoords));
+   vec2 fra = fract(texCoords);
+   texSize -= 1;
+
+   const mat4 CatMul = mat4(0, 1, 0, 0, -0.5, 0, 0.5, 0, 1, -2.5, 2, -0.5, -0.5, 1.5, -1.5, 0.5);
+   vec4 xx = CatMul * vec4(1.0, fra.x, fra.x*fra.x, fra.x*fra.x*fra.x);
+   vec4 yy = CatMul * vec4(1.0, fra.y, fra.y*fra.y, fra.y*fra.y*fra.y);
+
+   vec4 a00 = texelFetch(sampler, clamp(texel + ivec2(-1, -1), ivec2(0, 0), texSize), 0) * xx.x;
+   vec4 a01 = texelFetch(sampler, clamp(texel + ivec2( 0, -1), ivec2(0, 0), texSize), 0) * xx.y;
+   vec4 a02 = texelFetch(sampler, clamp(texel + ivec2( 1, -1), ivec2(0, 0), texSize), 0) * xx.z;
+   vec4 a03 = texelFetch(sampler, clamp(texel + ivec2( 2, -1), ivec2(0, 0), texSize), 0) * xx.w;
+   vec4 a10 = texelFetch(sampler, clamp(texel + ivec2(-1,  0), ivec2(0, 0), texSize), 0) * xx.x;
+   vec4 a11 = texelFetch(sampler, clamp(texel + ivec2( 0,  0), ivec2(0, 0), texSize), 0) * xx.y;
+   vec4 a12 = texelFetch(sampler, clamp(texel + ivec2( 1,  0), ivec2(0, 0), texSize), 0) * xx.z;
+   vec4 a13 = texelFetch(sampler, clamp(texel + ivec2( 2,  0), ivec2(0, 0), texSize), 0) * xx.w;
+   vec4 a20 = texelFetch(sampler, clamp(texel + ivec2(-1,  1), ivec2(0, 0), texSize), 0) * xx.x;
+   vec4 a21 = texelFetch(sampler, clamp(texel + ivec2( 0,  1), ivec2(0, 0), texSize), 0) * xx.y;
+   vec4 a22 = texelFetch(sampler, clamp(texel + ivec2( 1,  1), ivec2(0, 0), texSize), 0) * xx.z;
+   vec4 a23 = texelFetch(sampler, clamp(texel + ivec2( 2,  1), ivec2(0, 0), texSize), 0) * xx.w;
+   vec4 a30 = texelFetch(sampler, clamp(texel + ivec2(-1,  2), ivec2(0, 0), texSize), 0) * xx.x;
+   vec4 a31 = texelFetch(sampler, clamp(texel + ivec2( 0,  2), ivec2(0, 0), texSize), 0) * xx.y;
+   vec4 a32 = texelFetch(sampler, clamp(texel + ivec2( 1,  2), ivec2(0, 0), texSize), 0) * xx.z;
+   vec4 a33 = texelFetch(sampler, clamp(texel + ivec2( 2,  2), ivec2(0, 0), texSize), 0) * xx.w;
+
+   vec4 c = vec4(0.0);
+   c += (a00 + a01 + a02 + a03) * yy.x;
+   c += (a10 + a11 + a12 + a13) * yy.y;
+   c += (a20 + a21 + a22 + a23) * yy.z;
+   c += (a30 + a31 + a32 + a33) * yy.w;
+
+   return c;
+}
+
 void main(void)
 {
-    color = texture(qt_Texture0, qt_TexCoord0);
+    switch(filtering)
+    {
+    case 0://nearest
+        color = texelFetch(qt_Texture0, ivec2(qt_TexCoord0 * textureSize(qt_Texture0, 0)), 0);
+        break;
+    default:
+    case 1://bilinear
+        color = texture(qt_Texture0, qt_TexCoord0);
+        break;
+    case 2://catmul bicubic
+        color = textureCatmul(qt_Texture0, qt_TexCoord0);
+        break;
+    }
+
     color.rgb = color.rgb * unit_scale.x + unit_scale.y;
     if(bw)color = color.rrra;
     color = MTF(color, vec4(mtf_param[0], 0.0), vec4(mtf_param[1], 0.5), vec4(mtf_param[2], 1.0));