291 lines
9.9 KiB
C++
291 lines
9.9 KiB
C++
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#include "touch.h"
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#include <algorithm>
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#include <stack>
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#include "svga.h"
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namespace fallout {
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#define TOUCH_PHASE_BEGAN 0
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#define TOUCH_PHASE_MOVED 1
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#define TOUCH_PHASE_ENDED 2
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#define MAX_TOUCHES 10
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#define TAP_MAXIMUM_DURATION 75
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#define PAN_MINIMUM_MOVEMENT 4
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#define LONG_PRESS_MINIMUM_DURATION 500
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struct TouchLocation {
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int x;
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int y;
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};
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struct Touch {
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bool used;
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SDL_FingerID fingerId;
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TouchLocation startLocation;
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Uint32 startTimestamp;
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TouchLocation currentLocation;
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Uint32 currentTimestamp;
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int phase;
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};
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static Touch touches[MAX_TOUCHES];
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static Gesture currentGesture;
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static std::stack<Gesture> gestureEventsQueue;
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static int find_touch(SDL_FingerID fingerId)
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{
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for (int index = 0; index < MAX_TOUCHES; index++) {
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if (touches[index].fingerId == fingerId) {
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return index;
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}
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}
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return -1;
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}
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static int find_unused_touch_index()
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{
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for (int index = 0; index < MAX_TOUCHES; index++) {
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if (!touches[index].used) {
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return index;
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}
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}
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return -1;
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}
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static TouchLocation touch_get_start_location_centroid(int* indexes, int length)
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{
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TouchLocation centroid;
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centroid.x = 0;
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centroid.y = 0;
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for (int index = 0; index < length; index++) {
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centroid.x += touches[indexes[index]].startLocation.x;
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centroid.y += touches[indexes[index]].startLocation.y;
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}
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centroid.x /= length;
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centroid.y /= length;
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return centroid;
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}
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static TouchLocation touch_get_current_location_centroid(int* indexes, int length)
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{
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TouchLocation centroid;
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centroid.x = 0;
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centroid.y = 0;
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for (int index = 0; index < length; index++) {
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centroid.x += touches[indexes[index]].currentLocation.x;
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centroid.y += touches[indexes[index]].currentLocation.y;
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}
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centroid.x /= length;
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centroid.y /= length;
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return centroid;
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}
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void touch_handle_start(SDL_TouchFingerEvent* event)
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{
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// On iOS `fingerId` is an address of underlying `UITouch` object. When
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// `touchesBegan` is called this object might be reused, but with
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// incresed `tapCount` (which is ignored in this implementation).
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int index = find_touch(event->fingerId);
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if (index == -1) {
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index = find_unused_touch_index();
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}
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if (index != -1) {
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Touch* touch = &(touches[index]);
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touch->used = true;
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touch->fingerId = event->fingerId;
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touch->startTimestamp = event->timestamp;
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touch->startLocation.x = static_cast<int>(event->x * screenGetWidth());
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touch->startLocation.y = static_cast<int>(event->y * screenGetHeight());
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touch->currentTimestamp = touch->startTimestamp;
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touch->currentLocation = touch->startLocation;
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touch->phase = TOUCH_PHASE_BEGAN;
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}
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}
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void touch_handle_move(SDL_TouchFingerEvent* event)
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{
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int index = find_touch(event->fingerId);
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if (index != -1) {
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Touch* touch = &(touches[index]);
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touch->currentTimestamp = event->timestamp;
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touch->currentLocation.x = static_cast<int>(event->x * screenGetWidth());
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touch->currentLocation.y = static_cast<int>(event->y * screenGetHeight());
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touch->phase = TOUCH_PHASE_MOVED;
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}
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}
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void touch_handle_end(SDL_TouchFingerEvent* event)
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{
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int index = find_touch(event->fingerId);
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if (index != -1) {
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Touch* touch = &(touches[index]);
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touch->currentTimestamp = event->timestamp;
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touch->currentLocation.x = static_cast<int>(event->x * screenGetWidth());
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touch->currentLocation.y = static_cast<int>(event->y * screenGetHeight());
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touch->phase = TOUCH_PHASE_ENDED;
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}
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}
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void touch_process_gesture()
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{
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Uint32 sequenceStartTimestamp = -1;
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int sequenceStartIndex = -1;
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// Find start of sequence (earliest touch).
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for (int index = 0; index < MAX_TOUCHES; index++) {
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if (touches[index].used) {
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if (sequenceStartTimestamp > touches[index].startTimestamp) {
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sequenceStartTimestamp = touches[index].startTimestamp;
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sequenceStartIndex = index;
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}
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}
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}
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if (sequenceStartIndex == -1) {
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return;
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}
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Uint32 sequenceEndTimestamp = -1;
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if (touches[sequenceStartIndex].phase == TOUCH_PHASE_ENDED) {
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sequenceEndTimestamp = touches[sequenceStartIndex].currentTimestamp;
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// Find end timestamp of sequence.
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for (int index = 0; index < MAX_TOUCHES; index++) {
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if (touches[index].used
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&& touches[index].startTimestamp >= sequenceStartTimestamp
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&& touches[index].startTimestamp <= sequenceEndTimestamp) {
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if (touches[index].phase == TOUCH_PHASE_ENDED) {
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if (sequenceEndTimestamp < touches[index].currentTimestamp) {
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sequenceEndTimestamp = touches[index].currentTimestamp;
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// Start over since we can have fingers missed.
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index = -1;
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}
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} else {
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// Sequence is current.
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sequenceEndTimestamp = -1;
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break;
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}
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}
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}
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}
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int active[MAX_TOUCHES];
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int activeCount = 0;
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int ended[MAX_TOUCHES];
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int endedCount = 0;
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// Split participating fingers into two buckets - active fingers (currently
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// on screen) and ended (lifted up).
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for (int index = 0; index < MAX_TOUCHES; index++) {
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if (touches[index].used
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&& touches[index].currentTimestamp >= sequenceStartTimestamp
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&& touches[index].currentTimestamp <= sequenceEndTimestamp) {
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if (touches[index].phase == TOUCH_PHASE_ENDED) {
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ended[endedCount++] = index;
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} else {
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active[activeCount++] = index;
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}
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// If this sequence is over, unmark participating finger as used.
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if (sequenceEndTimestamp != -1) {
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touches[index].used = false;
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}
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}
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}
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if (currentGesture.type == kPan || currentGesture.type == kLongPress) {
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if (currentGesture.state != kEnded) {
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// For continuous gestures we want number of fingers to remain the
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// same as it was when gesture was recognized.
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if (activeCount == currentGesture.numberOfTouches && endedCount == 0) {
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TouchLocation centroid = touch_get_current_location_centroid(active, activeCount);
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currentGesture.state = kChanged;
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currentGesture.x = centroid.x;
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currentGesture.y = centroid.y;
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gestureEventsQueue.push(currentGesture);
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} else {
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currentGesture.state = kEnded;
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gestureEventsQueue.push(currentGesture);
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}
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}
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// Reset continuous gesture if when current sequence is over.
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if (currentGesture.state == kEnded && sequenceEndTimestamp != -1) {
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currentGesture.type = kUnrecognized;
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}
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} else {
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if (activeCount == 0 && endedCount != 0) {
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// For taps we need all participating fingers to be both started
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// and ended simultaneously (within predefined threshold).
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Uint32 startEarliestTimestamp = -1;
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Uint32 startLatestTimestamp = 0;
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Uint32 endEarliestTimestamp = -1;
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Uint32 endLatestTimestamp = 0;
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for (int index = 0; index < endedCount; index++) {
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startEarliestTimestamp = std::min(startEarliestTimestamp, touches[ended[index]].startTimestamp);
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startLatestTimestamp = std::max(startLatestTimestamp, touches[ended[index]].startTimestamp);
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endEarliestTimestamp = std::min(endEarliestTimestamp, touches[ended[index]].currentTimestamp);
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endLatestTimestamp = std::max(endLatestTimestamp, touches[ended[index]].currentTimestamp);
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}
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if (startLatestTimestamp - startEarliestTimestamp <= TAP_MAXIMUM_DURATION
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&& endLatestTimestamp - endEarliestTimestamp <= TAP_MAXIMUM_DURATION) {
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TouchLocation currentCentroid = touch_get_current_location_centroid(ended, endedCount);
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currentGesture.type = kTap;
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currentGesture.state = kEnded;
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currentGesture.numberOfTouches = endedCount;
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currentGesture.x = currentCentroid.x;
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currentGesture.y = currentCentroid.y;
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gestureEventsQueue.push(currentGesture);
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// Reset tap gesture immediately.
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currentGesture.type = kUnrecognized;
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}
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} else if (activeCount != 0 && endedCount == 0) {
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TouchLocation startCentroid = touch_get_start_location_centroid(active, activeCount);
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TouchLocation currentCentroid = touch_get_current_location_centroid(active, activeCount);
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// Disambiguate between pan and long press.
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if (abs(currentCentroid.x - startCentroid.x) >= PAN_MINIMUM_MOVEMENT
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|| abs(currentCentroid.y - startCentroid.y) >= PAN_MINIMUM_MOVEMENT) {
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currentGesture.type = kPan;
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currentGesture.state = kBegan;
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currentGesture.numberOfTouches = activeCount;
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currentGesture.x = currentCentroid.x;
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currentGesture.y = currentCentroid.y;
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gestureEventsQueue.push(currentGesture);
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} else if (SDL_GetTicks() - touches[active[0]].startTimestamp >= LONG_PRESS_MINIMUM_DURATION) {
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currentGesture.type = kLongPress;
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currentGesture.state = kBegan;
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currentGesture.numberOfTouches = activeCount;
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currentGesture.x = currentCentroid.x;
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currentGesture.y = currentCentroid.y;
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gestureEventsQueue.push(currentGesture);
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}
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}
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}
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}
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bool touch_get_gesture(Gesture* gesture)
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{
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if (gestureEventsQueue.empty()) {
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return false;
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}
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*gesture = gestureEventsQueue.top();
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gestureEventsQueue.pop();
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return true;
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}
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} // namespace fallout
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