From 94b8e3b80f3771bfe7ea799aed5895f729b06271 Mon Sep 17 00:00:00 2001
From: Henrik Rydberg <rydberg@euromail.se>
Date: Mon, 18 Oct 2010 18:12:07 +0200
Subject: [PATCH 2/2] Use a unified pointer emulation model

The existing kernel MT devices together use a handful of different
pointer emulation strategies, each with its own subtlety. This creates
a problem for grail, which needs to rebuild pointer emulation during
gesture recognition; relying on the correct pointer information to be
available at the right time becomes almost impossible.

This patch implements a common pointer emulation model for grail,
following a strategy recently discussed on LKML. This resolves the
problems stemming from different emulation strategies, and results
in a common pointer emulation experience for all devices.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
 src/grail-api.c  |   60 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 src/grail-impl.h |    1 +
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/src/grail-api.c b/src/grail-api.c
index 9cc94df..f013aa3 100644
--- a/src/grail-api.c
+++ b/src/grail-api.c
@@ -36,10 +36,6 @@ static void tp_event(struct touch_dev *dev,
 	struct grail *ge = dev->priv;
 	struct grail_impl *x = ge->impl;
 	if (ev->type == EV_ABS) {
-		if (ev->code == ABS_X)
-			x->pointer_x = ev->value;
-		if (ev->code == ABS_Y)
-			x->pointer_y = ev->value;
 		return;
 	}
 	if (ev->type == EV_KEY) {
@@ -80,6 +76,60 @@ static void report_up(struct grail_impl *impl, const struct input_event *syn)
 	impl->report_status = 0;
 }
 
+#define SYSCALL(call) while (((call) == -1) && (errno == EINTR))
+
+static int getabs(struct input_absinfo *abs, int key, int fd)
+{
+	int rc;
+	SYSCALL(rc = ioctl(fd, EVIOCGABS(key), abs));
+	return rc >= 0;
+}
+
+static void set_emulation_caps(struct grail_impl *impl, int fd)
+{
+	struct touch_caps *emu = &impl->emu;
+	struct input_absinfo info;
+
+	memset(emu, 0, sizeof(*emu));
+
+	if (getabs(&info, ABS_X, fd)) {
+		emu->min_x = info.minimum;
+		emu->max_x = info.maximum;
+	}
+	if (getabs(&info, ABS_Y, fd)) {
+		emu->min_y = info.minimum;
+		emu->max_y = info.maximum;
+	}
+}
+
+static void set_pointer(struct grail_impl *impl)
+{
+	struct touch_dev *dev = &impl->dev;
+	struct touch_caps *caps = &dev->caps;
+	struct touch_caps *emu = &impl->emu;
+	struct touch_frame *frame = &dev->frame;
+	int best_x, best_y, best_d = -1;
+	int i;
+
+	for (i = 0; i < frame->nactive; i++) {
+		struct touch *t = frame->active[i];
+		float u = (t->x - caps->min_x) / (caps->max_x - caps->min_x);
+		float v = (t->y - caps->min_y) / (caps->max_y - caps->min_y);
+		int x = emu->min_x + u * (emu->max_x - emu->min_x);
+		int y = emu->min_y + v * (emu->max_y - emu->min_y);
+		int d = abs(x - impl->pointer_x) + abs(y - impl->pointer_y);
+		if (best_d < 0 || d < best_d) {
+			best_x = x;
+			best_y = y;
+			best_d = d;
+		}
+	}
+	if (best_d >= 0) {
+		impl->pointer_x = best_x;
+		impl->pointer_y = best_y;
+	}
+}
+
 static void handle_abs_events(struct grail *ge, const struct input_event *syn)
 {
 	static const int fm_mask = 0x03;
@@ -95,6 +145,7 @@ static void handle_abs_events(struct grail *ge, const struct input_event *syn)
 	int ishold = pointer && tap->active && !used_move;
 	int istap = gru->tapping.tap == 1 && !used_tap;
 
+	set_pointer(impl);
 	if (!impl->pointer_status && pointer) {
 		impl->report_x = impl->pointer_x;
 		impl->report_y = impl->pointer_y;
@@ -175,6 +226,7 @@ int grail_open(struct grail *ge, int fd)
 	ret = touch_dev_open(&x->dev, fd);
 	if (ret)
 		goto freemem;
+	set_emulation_caps(x, fd);
 	x->dev.event = tp_event;
 	x->dev.sync = tp_sync;
 	x->dev.priv = ge;
diff --git a/src/grail-impl.h b/src/grail-impl.h
index 6093a0f..dc3b425 100644
--- a/src/grail-impl.h
+++ b/src/grail-impl.h
@@ -28,6 +28,7 @@
 
 struct grail_impl {
 	struct touch_dev dev;
+	struct touch_caps emu;
 	struct evbuf evbuf;
 	int filter_abs;
 	int pointer_status;
-- 
1.7.1