clients: Add a touchscreen calibration tool

This a basic calibration tool designed for "in factory" calibration of a touch
screen. The constants for the calibration functions:

x' = Ax + By + C and
y' = Dx + Ey + F

Are printed on stdout when the calibration is completed.

clients/Makefile.am

@@ -63,6 +63,7 @@ clients_programs =				\
 	clickdot				\
 	editor					\
 	transformed				\
+	calibrator				\
 	$(full_gl_client_programs)
 
 desktop_shell = weston-desktop-shell
@@ -122,6 +123,9 @@ clickdot_LDADD = $(toolkit_libs)
 transformed_SOURCES = transformed.c
 transformed_LDADD = $(toolkit_libs)
 
+calibrator_SOURCES = calibrator.c
+calibrator_LDADD = $(toolkit_libs)
+
 editor_SOURCES = 				\
 	editor.c				\
 	text-protocol.c				\

clients/calibrator.c

@@ -0,0 +1,260 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <cairo.h>
+#include <math.h>
+#include <assert.h>
+
+#include <linux/input.h>
+#include <wayland-client.h>
+
+#include "window.h"
+#include "../shared/matrix.h"
+
+#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
+
+/* Our points for the calibration must be not be on a line */
+static const struct {
+	float x_ratio, y_ratio;
+} test_ratios[] =  {
+	{ 0.20, 0.40 },
+	{ 0.80, 0.60 },
+	{ 0.40, 0.80 }
+};
+
+struct calibrator {
+	struct tests {
+		int32_t drawn_x, drawn_y;
+		int32_t clicked_x, clicked_y;
+	} tests[ARRAY_LENGTH(test_ratios)];
+	int current_test;
+
+	struct display *display;
+	struct window *window;
+	struct widget *widget;
+};
+
+/*
+ * Calibration algorithm:
+ *
+ * The equation we want to apply at event time where x' and y' are the
+ * calibrated co-ordinates.
+ *
+ * x' = Ax + By + C
+ * y' = Dx + Ey + F
+ *
+ * For example "zero calibration" would be A=1.0 B=0.0 C=0.0, D=0.0, E=1.0,
+ * and F=0.0.
+ *
+ * With 6 unknowns we need 6 equations to find the constants:
+ *
+ * x1' = Ax1 + By1 + C
+ * y1' = Dx1 + Ey1 + F
+ * ...
+ * x3' = Ax3 + By3 + C
+ * y3' = Dx3 + Ey3 + F
+ *
+ * In matrix form:
+ *
+ * x1'   x1 y1 1      A
+ * x2' = x2 y2 1  x   B
+ * x3'   x3 y3 1      C
+ *
+ * So making the matrix M we can find the constants with:
+ *
+ * A            x1'
+ * B = M^-1  x  x2'
+ * C            x3'
+ *
+ * (and similarly for D, E and F)
+ *
+ * For the calibration the desired values x, y are the same values at which
+ * we've drawn at.
+ *
+ */
+static void
+finish_calibration (struct calibrator *calibrator)
+{
+	struct weston_matrix m;
+	struct weston_matrix inverse;
+	struct weston_vector x_calib, y_calib;
+	int i;
+
+
+	/*
+	 * x1 y1  1  0
+	 * x2 y2  1  0
+	 * x3 y3  1  0
+	 *  0  0  0  1
+	 */
+	memset(&m, 0, sizeof(m));
+	for (i = 0; i < (int)ARRAY_LENGTH(test_ratios); i++) {
+		m.d[i] = calibrator->tests[i].clicked_x;
+		m.d[i + 4] = calibrator->tests[i].clicked_y;
+		m.d[i + 8] = 1;
+	}
+	m.d[15] = 1;
+
+	weston_matrix_invert(&inverse, &m);
+
+	memset(&x_calib, 0, sizeof(x_calib));
+	memset(&y_calib, 0, sizeof(y_calib));
+
+	for (i = 0; i < (int)ARRAY_LENGTH(test_ratios); i++) {
+		x_calib.f[i] = calibrator->tests[i].drawn_x;
+		y_calib.f[i] = calibrator->tests[i].drawn_y;
+	}
+
+	/* Multiples into the vector */
+	weston_matrix_transform(&inverse, &x_calib);
+	weston_matrix_transform(&inverse, &y_calib);
+
+	printf ("Calibration values: %f %f %f %f %f %f\n",
+		x_calib.f[0], x_calib.f[1], x_calib.f[2],
+		y_calib.f[0], y_calib.f[1], y_calib.f[2]);
+
+	exit(0);
+}
+
+
+static void
+button_handler(struct widget *widget,
+	       struct input *input, uint32_t time,
+	       uint32_t button,
+	       enum wl_pointer_button_state state, void *data)
+{
+	struct calibrator *calibrator = data;
+	int32_t x, y;
+
+	if (state == WL_POINTER_BUTTON_STATE_PRESSED && button == BTN_LEFT) {
+		input_get_position(input, &x, &y);
+		calibrator->tests[calibrator->current_test].clicked_x = x;
+		calibrator->tests[calibrator->current_test].clicked_y = y;
+
+		calibrator->current_test--;
+		if (calibrator->current_test < 0)
+			finish_calibration(calibrator);
+	}
+
+	widget_schedule_redraw(widget);
+}
+
+static void
+redraw_handler(struct widget *widget, void *data)
+{
+	struct calibrator *calibrator = data;
+	struct rectangle allocation;
+	cairo_surface_t *surface;
+	cairo_t *cr;
+	int32_t drawn_x, drawn_y;
+
+	widget_get_allocation(calibrator->widget, &allocation);
+	surface = window_get_surface(calibrator->window);
+
+	cr = cairo_create(surface);
+	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+	cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 1.0);
+	cairo_paint(cr);
+
+	drawn_x = test_ratios[calibrator->current_test].x_ratio * allocation.width;
+	drawn_y = test_ratios[calibrator->current_test].y_ratio * allocation.height;
+
+	calibrator->tests[calibrator->current_test].drawn_x = drawn_x;
+	calibrator->tests[calibrator->current_test].drawn_y = drawn_y;
+
+	cairo_translate(cr, drawn_x, drawn_y);
+	cairo_set_line_width(cr, 2.0);
+	cairo_set_source_rgb(cr, 1.0, 0.0, 0.0);
+	cairo_move_to(cr, 0, -10.0);
+	cairo_line_to(cr, 0, 10.0);
+	cairo_stroke(cr);
+	cairo_move_to(cr, -10.0, 0);
+	cairo_line_to(cr, 10.0, 0.0);
+	cairo_stroke(cr);
+
+	cairo_destroy(cr);
+	cairo_surface_destroy(surface);
+}
+
+static struct calibrator *
+calibrator_create(struct display *display)
+{
+	struct calibrator *calibrator;
+
+	calibrator = malloc(sizeof *calibrator);
+	if (calibrator == NULL)
+		return NULL;
+
+	calibrator->window = window_create(display);
+	calibrator->widget = window_add_widget(calibrator->window, calibrator);
+	window_set_title(calibrator->window, "Wayland calibrator");
+	calibrator->display = display;
+
+	calibrator->current_test = ARRAY_LENGTH(test_ratios) - 1;
+
+	widget_set_button_handler(calibrator->widget, button_handler);
+	widget_set_redraw_handler(calibrator->widget, redraw_handler);
+
+	window_set_fullscreen(calibrator->window, 1);
+
+	return calibrator;
+}
+
+static void
+calibrator_destroy(struct calibrator *calibrator)
+{
+	widget_destroy(calibrator->widget);
+	window_destroy(calibrator->window);
+	free(calibrator);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+	struct display *display;
+	struct calibrator *calibrator;
+
+	display = display_create(argc, argv);
+
+	if (display == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return -1;
+	}
+
+	calibrator = calibrator_create(display);
+
+	if (!calibrator)
+		return -1;
+
+	display_run(display);
+
+	calibrator_destroy(calibrator);
+	display_destroy(display);
+
+	return 0;
+}
+