Properly calibrate the input device

src/calibrator.cpp

@@ -148,18 +148,29 @@ bool Calibrator::finish(int width, int height)
     // based on old_axys: inversion/swapping is relative to the old axis
     XYinfo new_axis(old_axys);
 
-
-    // calculate average of clicks
-    float x_min = (clicked.x[UL] + clicked.x[LL])/2.0;
-    float x_max = (clicked.x[UR] + clicked.x[LR])/2.0;
-    float y_min = (clicked.y[UL] + clicked.y[UR])/2.0;
-    float y_max = (clicked.y[LL] + clicked.y[LR])/2.0;
-
-    // Should x and y be swapped?
-    if (abs(clicked.x[UL] - clicked.x[UR]) < abs(clicked.y[UL] - clicked.y[UR])) {
-        new_axis.swap_xy = !new_axis.swap_xy;
-        std::swap(x_min, y_min);
-        std::swap(x_max, y_max);
+    // Calculate average of clicks.
+    // Set min and max values depending on the sequence of the clicked coordinates.
+    // If first two clicks have different x coordinates, we have a 0 or 180
+    // degrees rotation else we have a 70 or 270 degrees rotation.
+    float x_min;
+    float x_max;
+    float y_min;
+    float y_max;
+    if(abs(clicked.x[UL] - clicked.x[LL]) < abs(clicked.x[UL] - clicked.x[UR])) {
+        // rotation of 0 or 180 degrees
+        x_min = (clicked.x[UL] + clicked.x[LL])/2.0;
+        x_max = (clicked.x[UR] + clicked.x[LR])/2.0;
+        y_min = (clicked.y[UL] + clicked.y[UR])/2.0;
+        y_max = (clicked.y[LL] + clicked.y[LR])/2.0;
+    } else {
+        // rotation of 90 or 270 degreees
+        x_min = (clicked.x[UL] + clicked.x[UR])/2.0;
+        x_max = (clicked.x[LL] + clicked.x[LR])/2.0;
+        y_min = (clicked.y[UL] + clicked.y[LL])/2.0;
+        y_max = (clicked.y[UR] + clicked.y[LR])/2.0;
+
+        // axes are swapped on 90 or 270 degrees rotation
+        new_axis.swap_xy = !old_axys.swap_xy;
     }
 
     // the screen was divided in num_blocks blocks, and the touch points were at
@@ -185,6 +196,11 @@ bool Calibrator::finish(int width, int height)
     y_min = scaleAxis(y_min, old_axys.y.max, old_axys.y.min, height, 0);
     y_max = scaleAxis(y_max, old_axys.y.max, old_axys.y.min, height, 0);
 
+    // If we swapped axes also swap x and y values
+    if(new_axis.swap_xy != old_axys.swap_xy) {
+        std::swap(x_min, y_min);
+        std::swap(x_max, y_max);
+    }
 
     // round and put in new_axis struct
     new_axis.x.min = round(x_min); new_axis.x.max = round(x_max);

src/calibrator/Evdev.cpp

@@ -189,13 +189,30 @@ bool CalibratorEvdev::finish(int width, int height)
     // based on old_axys: inversion/swapping is relative to the old axis
     XYinfo new_axis(old_axys);
 
-
-    // calculate average of clicks
-    float x_min = (clicked.x[UL] + clicked.x[LL])/2.0;
-    float x_max = (clicked.x[UR] + clicked.x[LR])/2.0;
-    float y_min = (clicked.y[UL] + clicked.y[UR])/2.0;
-    float y_max = (clicked.y[LL] + clicked.y[LR])/2.0;
-
+    // Calculate average of clicks.
+    // Set min and max values depending on the sequence of the clicked coordinates.
+    // If first two clicks have different x coordinates, we have a 0 or 180
+    // degrees rotation else we have a 70 or 270 degrees rotation.
+    float x_min;
+    float x_max;
+    float y_min;
+    float y_max;
+    if(abs(clicked.x[UL] - clicked.x[LL]) < abs(clicked.x[UL] - clicked.x[UR])) {
+        // rotation of 0 or 180 degrees
+        x_min = (clicked.x[UL] + clicked.x[LL])/2.0;
+        x_max = (clicked.x[UR] + clicked.x[LR])/2.0;
+        y_min = (clicked.y[UL] + clicked.y[UR])/2.0;
+        y_max = (clicked.y[LL] + clicked.y[LR])/2.0;
+    } else {
+        // rotation of 90 or 270 degreees
+        x_min = (clicked.x[UL] + clicked.x[UR])/2.0;
+        x_max = (clicked.x[LL] + clicked.x[LR])/2.0;
+        y_min = (clicked.y[UL] + clicked.y[LL])/2.0;
+        y_max = (clicked.y[UR] + clicked.y[LR])/2.0;
+
+        // axes are swapped on 90 or 270 degrees rotation
+        new_axis.swap_xy = !old_axys.swap_xy;
+    }
 
     // When evdev detects an invert_X/Y option,
     // it performs the following *crazy* code just before returning
@@ -217,14 +234,6 @@ bool CalibratorEvdev::finish(int width, int height)
     }
     // end of evdev inversion crazyness
 
-
-    // Should x and y be swapped?
-    if (abs(clicked.x[UL] - clicked.x[UR]) < abs(clicked.y[UL] - clicked.y[UR])) {
-        new_axis.swap_xy = !new_axis.swap_xy;
-        std::swap(x_min, y_min);
-        std::swap(x_max, y_max);
-    }
-
     // the screen was divided in num_blocks blocks, and the touch points were at
     // one block away from the true edges of the screen.
     const float block_x = width/(float)num_blocks;
@@ -238,7 +247,7 @@ bool CalibratorEvdev::finish(int width, int height)
     float scale_y = (y_max - y_min)/(height - 2*block_y);
     y_min -= block_y * scale_y;
     y_max += block_y * scale_y;
-    
+
     // now, undo the transformations done by the X server, to obtain the true 'raw' value in X.
     // The raw value was scaled from old_axis to the device min/max, and from the device min/max
     // to the screen min/max
@@ -248,6 +257,11 @@ bool CalibratorEvdev::finish(int width, int height)
     y_min = scaleAxis(y_min, old_axys.y.max, old_axys.y.min, height, 0);
     y_max = scaleAxis(y_max, old_axys.y.max, old_axys.y.min, height, 0);
 
+    // If we swapped axes also swap x and y values
+    if(new_axis.swap_xy != old_axys.swap_xy) {
+        std::swap(x_min, y_min);
+        std::swap(x_max, y_max);
+    }
 
     // round and put in new_axis struct
     new_axis.x.min = round(x_min); new_axis.x.max = round(x_max);

src/tester.cpp

@@ -70,6 +70,8 @@ int main() {
         printf("Old axis: "); old_axis.print();
 
     for (unsigned c=0; c != raw_coords.size(); c++) {
+
+    for (unsigned s=0; s<=1; s++) {
         XYinfo raw(raw_coords[c]);
         //printf("Raw: "); raw.print();
 
@@ -84,10 +86,19 @@ int main() {
         //printf("\tClicked: "); clicked.print();
 
         // emulate screen clicks
-        calib->add_click(clicked.x.min, clicked.y.min);
-        calib->add_click(clicked.x.max, clicked.y.min);
-        calib->add_click(clicked.x.min, clicked.y.max);
-        calib->add_click(clicked.x.max, clicked.y.max);
+        // Depending on the sequence of clicks the first changed coordinate can
+        // be either x or y so we emulate both possible sequences
+        if(!s) {
+            calib->add_click(clicked.x.min, clicked.y.min);
+            calib->add_click(clicked.x.max, clicked.y.min);
+            calib->add_click(clicked.x.min, clicked.y.max);
+            calib->add_click(clicked.x.max, clicked.y.max);
+        } else {
+            calib->add_click(clicked.x.min, clicked.y.min);
+            calib->add_click(clicked.x.min, clicked.y.max);
+            calib->add_click(clicked.x.max, clicked.y.min);
+            calib->add_click(clicked.x.max, clicked.y.max);
+        }
         calib->finish(width, height);
 
         // test result
@@ -112,6 +123,8 @@ int main() {
         printf("%i", maxdiff);
     } // loop over raw_coords
 
+    } // loop over sequences
+
         printf(". OK\n");
     } // loop over old_axes