Using qreal more consistently in code (prevent misuse of double)

We want to force use of qreal where possible. This can lead to better
performance on platforms where qreal -> float (i.e. ARM). To achieve
this we:

1. changed from 'double' to 'qreal', where justified
2. using qreal() to intialize constants, where justified
3. adding helper functions that are overloaded for qreal
   like qAtan2(), qAcos(), qFabs() ...
4. defining QT_USE_MATH_H_FLOATS for Symbian platform

In addtion we used opportunity to improve code with some small things
5. converting divisions to multiplications
   (i.e. '/ 2.0' -> '* qreal(0.5)')
6. defining new constants (i.e. 'Q_PI / 180.0' -> 'Q_PI180')
7. declaring variables as 'const', where justified

Reviewed-by: Andreas Aardal Hanssen
Reviewed-by: Gunnar Sletta
Reviewed-by: Jan-Arve
Reviewed-by: Kim Motoyoshi Kalland
Reviewed-by: Alessandro Portale
Reviewed-by: Janne Koskinen

1 files changed, 56 insertions, 55 deletions

diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
index 41602a1..b9f439e 100644
--- a/src/gui/painting/qdrawhelper.cpp
+++ b/src/gui/painting/qdrawhelper.cpp
@@ -565,8 +565,8 @@ const uint * QT_FASTCALL fetchTransformed(uint *buffer, const Operator *, const
     int image_width = data->texture.width;
     int image_height = data->texture.height;
 
-    const qreal cx = x + 0.5;
-    const qreal cy = y + 0.5;
+    const qreal cx = x + qreal(0.5);
+    const qreal cy = y + qreal(0.5);
 
     const uint *end = buffer + length;
     uint *b = buffer;
@@ -670,8 +670,8 @@ const uint * QT_FASTCALL fetchTransformedBilinear(uint *buffer, const Operator *
     int image_width = data->texture.width;
     int image_height = data->texture.height;
 
-    const qreal cx = x + 0.5;
-    const qreal cy = y + 0.5;
+    const qreal cx = x + qreal(0.5);
+    const qreal cy = y + qreal(0.5);
 
     const uint *end = buffer + length;
     uint *b = buffer;
@@ -747,8 +747,8 @@ const uint * QT_FASTCALL fetchTransformedBilinear(uint *buffer, const Operator *
 
         while (b < end) {
             const qreal iw = fw == 0 ? 1 : 1 / fw;
-            const qreal px = fx * iw - 0.5;
-            const qreal py = fy * iw - 0.5;
+            const qreal px = fx * iw - qreal(0.5);
+            const qreal py = fy * iw - qreal(0.5);
 
             int x1 = int(px) - (px < 0);
             int x2 = x1 + 1;
@@ -927,7 +927,7 @@ static const SourceFetchProc sourceFetch[NBlendTypes][QImage::NImageFormats] = {
 
 static inline uint qt_gradient_pixel(const QGradientData *data, qreal pos)
 {
-    int ipos = int(pos * (GRADIENT_STOPTABLE_SIZE - 1) + 0.5);
+    int ipos = int(pos * (GRADIENT_STOPTABLE_SIZE - 1) + qreal(0.5));
 
   // calculate the actual offset.
     if (ipos < 0 || ipos >= GRADIENT_STOPTABLE_SIZE) {
@@ -1008,8 +1008,8 @@ static const uint * QT_FASTCALL fetchLinearGradient(uint *buffer, const Operator
     if (op->linear.l == 0) {
         t = inc = 0;
     } else {
-        rx = data->m21 * (y + 0.5) + data->m11 * (x + 0.5) + data->dx;
-        ry = data->m22 * (y + 0.5) + data->m12 * (x + 0.5) + data->dy;
+        rx = data->m21 * (y + qreal(0.5)) + data->m11 * (x + qreal(0.5)) + data->dx;
+        ry = data->m22 * (y + qreal(0.5)) + data->m12 * (x + qreal(0.5)) + data->dy;
         t = op->linear.dx*rx + op->linear.dy*ry + op->linear.off;
         inc = op->linear.dx * data->m11 + op->linear.dy * data->m12;
         affine = !data->m13 && !data->m23;
@@ -1045,7 +1045,7 @@ static const uint * QT_FASTCALL fetchLinearGradient(uint *buffer, const Operator
             }
         }
     } else { // fall back to float math here as well
-        qreal rw = data->m23 * (y + 0.5) + data->m13 * (x + 0.5) + data->m33;
+        qreal rw = data->m23 * (y + qreal(0.5)) + data->m13 * (x + qreal(0.5)) + data->m33;
         while (buffer < end) {
             qreal x = rx/rw;
             qreal y = ry/rw;
@@ -1092,10 +1092,10 @@ static const uint * QT_FASTCALL fetchRadialGradient(uint *buffer, const Operator
                                                     int y, int x, int length)
 {
     const uint *b = buffer;
-    qreal rx = data->m21 * (y + 0.5)
-               + data->dx + data->m11 * (x + 0.5);
-    qreal ry = data->m22 * (y + 0.5)
-               + data->dy + data->m12 * (x + 0.5);
+    qreal rx = data->m21 * (y + qreal(0.5))
+               + data->dx + data->m11 * (x + qreal(0.5));
+    qreal ry = data->m22 * (y + qreal(0.5))
+               + data->dy + data->m12 * (x + qreal(0.5));
     bool affine = !data->m13 && !data->m23;
     //qreal r  = data->gradient.radial.radius;
 
@@ -1141,8 +1141,8 @@ static const uint * QT_FASTCALL fetchRadialGradient(uint *buffer, const Operator
             ++buffer;
         }
     } else {
-        qreal rw = data->m23 * (y + 0.5)
-                   + data->m33 + data->m13 * (x + 0.5);
+        qreal rw = data->m23 * (y + qreal(0.5))
+                   + data->m33 + data->m13 * (x + qreal(0.5));
         if (!rw)
             rw = 1;
         while (buffer < end) {
@@ -1171,10 +1171,10 @@ static const uint * QT_FASTCALL fetchConicalGradient(uint *buffer, const Operato
                                                      int y, int x, int length)
 {
     const uint *b = buffer;
-    qreal rx = data->m21 * (y + 0.5)
-               + data->dx + data->m11 * (x + 0.5);
-    qreal ry = data->m22 * (y + 0.5)
-               + data->dy + data->m12 * (x + 0.5);
+    qreal rx = data->m21 * (y + qreal(0.5))
+               + data->dx + data->m11 * (x + qreal(0.5));
+    qreal ry = data->m22 * (y + qreal(0.5))
+               + data->dy + data->m12 * (x + qreal(0.5));
     bool affine = !data->m13 && !data->m23;
 
     const uint *end = buffer + length;
@@ -1182,25 +1182,25 @@ static const uint * QT_FASTCALL fetchConicalGradient(uint *buffer, const Operato
         rx -= data->gradient.conical.center.x;
         ry -= data->gradient.conical.center.y;
         while (buffer < end) {
-            qreal angle = atan2(ry, rx) + data->gradient.conical.angle;
+            qreal angle = qAtan2(ry, rx) + data->gradient.conical.angle;
 
-            *buffer = qt_gradient_pixel(&data->gradient, 1 - angle / (2*Q_PI));
+            *buffer = qt_gradient_pixel(&data->gradient, 1 - angle / Q_2PI);
 
             rx += data->m11;
             ry += data->m12;
             ++buffer;
         }
     } else {
-        qreal rw = data->m23 * (y + 0.5)
-                   + data->m33 + data->m13 * (x + 0.5);
+        qreal rw = data->m23 * (y + qreal(0.5))
+                   + data->m33 + data->m13 * (x + qreal(0.5));
         if (!rw)
             rw = 1;
         while (buffer < end) {
-            qreal angle = atan2(ry/rw - data->gradient.conical.center.x,
+            qreal angle = qAtan2(ry/rw - data->gradient.conical.center.x,
                                 rx/rw - data->gradient.conical.center.y)
                           + data->gradient.conical.angle;
 
-            *buffer = qt_gradient_pixel(&data->gradient, 1. - angle / (2*Q_PI));
+            *buffer = qt_gradient_pixel(&data->gradient, qreal(1.) - angle / Q_2PI);
 
             rx += data->m11;
             ry += data->m12;
@@ -5168,8 +5168,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_argb(int count, const
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             int x = int((data->m21 * cy
                          + data->m11 * cx + data->dx) * fixed_scale) - half_point;
@@ -5243,8 +5243,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_argb(int count, const
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             qreal x = data->m21 * cy + data->m11 * cx + data->dx;
             qreal y = data->m22 * cy + data->m12 * cx + data->dy;
@@ -5258,8 +5258,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_argb(int count, const
                 uint *b = buffer;
                 while (b < end) {
                     const qreal iw = w == 0 ? 1 : 1 / w;
-                    const qreal px = x * iw - 0.5;
-                    const qreal py = y * iw - 0.5;
+                    const qreal px = x * iw - qreal(0.5);
+                    const qreal py = y * iw - qreal(0.5);
 
                     int x1 = int(px) - (px < 0);
                     int x2 = x1 + 1;
@@ -5670,8 +5670,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_tiled_argb(int count,
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             int x = int((data->m21 * cy
                          + data->m11 * cx + data->dx) * fixed_scale) - half_point;
@@ -5753,8 +5753,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_tiled_argb(int count,
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             qreal x = data->m21 * cy + data->m11 * cx + data->dx;
             qreal y = data->m22 * cy + data->m12 * cx + data->dy;
@@ -5768,8 +5768,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_bilinear_tiled_argb(int count,
                 uint *b = buffer;
                 while (b < end) {
                     const qreal iw = w == 0 ? 1 : 1 / w;
-                    const qreal px = x * iw - 0.5;
-                    const qreal py = y * iw - 0.5;
+                    const qreal px = x * iw - qreal(0.5);
+                    const qreal py = y * iw - qreal(0.5);
 
                     int x1 = int(px) - (px < 0);
                     int x2 = x1 + 1;
@@ -5861,8 +5861,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_argb(int count, const QSpan *s
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             int x = int((data->m21 * cy
                          + data->m11 * cx + data->dx) * fixed_scale);
@@ -5909,8 +5909,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_argb(int count, const QSpan *s
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             qreal x = data->m21 * cy + data->m11 * cx + data->dx;
             qreal y = data->m22 * cy + data->m12 * cx + data->dy;
@@ -6261,8 +6261,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_tiled_argb(int count, const QS
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             int x = int((data->m21 * cy
                          + data->m11 * cx + data->dx) * fixed_scale);
@@ -6313,8 +6313,8 @@ Q_STATIC_TEMPLATE_FUNCTION void blend_transformed_tiled_argb(int count, const QS
             uint *target = ((uint *)t) + spans->x;
             uint *image_bits = (uint *)data->texture.imageData;
 
-            const qreal cx = spans->x + 0.5;
-            const qreal cy = spans->y + 0.5;
+            const qreal cx = spans->x + qreal(0.5);
+            const qreal cy = spans->y + qreal(0.5);
 
             qreal x = data->m21 * cy + data->m11 * cx + data->dx;
             qreal y = data->m22 * cy + data->m12 * cx + data->dy;
@@ -6998,7 +6998,7 @@ static void qt_gradient_quint32(int count, const QSpan *spans, void *userData)
          */
         const int gss = GRADIENT_STOPTABLE_SIZE - 1;
         int yinc = int((linear.dy * data->m22 * gss) * FIXPT_SIZE);
-        int off = int((((linear.dy * (data->m22 * 0.5 + data->dy) + linear.off) * gss) * FIXPT_SIZE));
+        int off = int((((linear.dy * (data->m22 * qreal(0.5) + data->dy) + linear.off) * gss) * FIXPT_SIZE));
 
         while (count--) {
             int y = spans->y;
@@ -7046,7 +7046,7 @@ static void qt_gradient_quint16(int count, const QSpan *spans, void *userData)
          */
         const int gss = GRADIENT_STOPTABLE_SIZE - 1;
         int yinc = int((linear.dy * data->m22 * gss) * FIXPT_SIZE);
-        int off = int((((linear.dy * (data->m22 * 0.5 + data->dy) + linear.off) * gss) * FIXPT_SIZE));
+        int off = int((((linear.dy * (data->m22 * qreal(0.5) + data->dy) + linear.off) * gss) * FIXPT_SIZE));
 
         uint oldColor = data->solid.color;
         while (count--) {
@@ -7125,13 +7125,13 @@ void qt_build_pow_tables() {
 #ifdef Q_WS_MAC
     // decided by testing a few things on an iMac, should probably get this from the
     // system...
-    smoothing = 2.0;
+    smoothing = qreal(2.0);
 #endif
 
 #ifdef Q_WS_WIN
     int winSmooth;
     if (SystemParametersInfo(0x200C /* SPI_GETFONTSMOOTHINGCONTRAST */, 0, &winSmooth, 0))
-        smoothing = winSmooth / 1000.0;
+        smoothing = winSmooth / qreal(1000.0);
 #endif
 
 #ifdef Q_WS_X11
@@ -7141,18 +7141,19 @@ void qt_build_pow_tables() {
         qt_pow_rgb_invgamma[i] = uchar(i);
     }
 #else
+    const qreal inv_255 = 1 / qreal(255.0);
     for (int i=0; i<256; ++i) {
-        qt_pow_rgb_gamma[i] = uchar(qRound(pow(i / qreal(255.0), smoothing) * 255));
-        qt_pow_rgb_invgamma[i] = uchar(qRound(pow(i / qreal(255.), 1 / smoothing) * 255));
+        qt_pow_rgb_gamma[i] = uchar(qRound(qPow(i * inv_255, smoothing) * 255));
+        qt_pow_rgb_invgamma[i] = uchar(qRound(qPow(i * inv_255, 1 / smoothing) * 255));
     }
 #endif
 
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
-    const qreal gray_gamma = 2.31;
+    const qreal gray_gamma = qreal(2.31);
     for (int i=0; i<256; ++i)
-        qt_pow_gamma[i] = uint(qRound(pow(i / qreal(255.), gray_gamma) * 2047));
+        qt_pow_gamma[i] = uint(qRound(qPow(i / qreal(255.), gray_gamma) * 2047));
     for (int i=0; i<2048; ++i)
-        qt_pow_invgamma[i] = uchar(qRound(pow(i / 2047.0, 1 / gray_gamma) * 255));
+        qt_pow_invgamma[i] = uchar(qRound(qPow(i / qreal(2047.0), 1 / gray_gamma) * 255));
 #endif
 }