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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* A stack of overlays that display itself and handle mouse events.
* TODO(kaznacheev) Consider disbanding this class and moving
* the functionality to individual objects that display anything or handle
* mouse events.
* @constructor
* @struct
*/
function ImageBuffer() {
this.overlays_ = [];
}
/**
* @typedef {function(number, number, boolean)}
*/
ImageBuffer.DragHandler;
/**
* Add an overlay to a buffer.
* @param {!ImageBuffer.Overlay} overlay An overlay added to a buffer.
*/
ImageBuffer.prototype.addOverlay = function(overlay) {
var zIndex = overlay.getZIndex();
// Store the overlays in the ascending Z-order.
var i;
for (i = 0; i != this.overlays_.length; i++) {
if (zIndex < this.overlays_[i].getZIndex()) break;
}
this.overlays_.splice(i, 0, overlay);
};
/**
* Remove an overlay from a buffer.
* @param {!ImageBuffer.Overlay} overlay An overlay removed from a buffer.
*/
ImageBuffer.prototype.removeOverlay = function(overlay) {
for (var i = 0; i != this.overlays_.length; i++) {
if (this.overlays_[i] == overlay) {
this.overlays_.splice(i, 1);
return;
}
}
throw new Error('Cannot remove overlay ' + overlay);
};
/**
* Draws overlays in the ascending Z-order.
*/
ImageBuffer.prototype.draw = function() {
for (var i = 0; i != this.overlays_.length; i++) {
this.overlays_[i].draw();
}
};
/**
* Searches for a cursor style in the descending Z-order.
* @param {number} x X coordinate for cursor.
* @param {number} y Y coordinate for cursor.
* @param {boolean} mouseDown If mouse button is down.
* @return {string} A value for style.cursor CSS property.
*/
ImageBuffer.prototype.getCursorStyle = function(x, y, mouseDown) {
for (var i = this.overlays_.length - 1; i >= 0; i--) {
var style = this.overlays_[i].getCursorStyle(x, y, mouseDown);
if (style) return style;
}
return 'default';
};
/**
* Searches for a click handler in the descending Z-order.
* @param {number} x X coordinate for click event.
* @param {number} y Y coordinate for click event.
* @return {boolean} True if handled.
*/
ImageBuffer.prototype.onClick = function(x, y) {
for (var i = this.overlays_.length - 1; i >= 0; i--) {
if (this.overlays_[i].onClick(x, y)) return true;
}
return false;
};
/**
* Searches for a drag handler in the descending Z-order.
* @param {number} x Event X coordinate.
* @param {number} y Event Y coordinate.
* @param {boolean} touch True if it's a touch event, false if mouse.
* @return {?ImageBuffer.DragHandler} A function to be called on mouse drag.
*/
ImageBuffer.prototype.getDragHandler = function(x, y, touch) {
for (var i = this.overlays_.length - 1; i >= 0; i--) {
var handler = this.overlays_[i].getDragHandler(x, y, touch);
if (handler)
return handler;
}
return null;
};
/**
* Searches for an action for the double tap enumerating
* layers in the descending Z-order.
* @param {number} x X coordinate of the event.
* @param {number} y Y coordinate of the event.
* @return {!ImageBuffer.DoubleTapAction} Action to perform as result.
*/
ImageBuffer.prototype.getDoubleTapAction = function(x, y) {
for (var i = this.overlays_.length - 1; i >= 0; i--) {
var action = this.overlays_[i].getDoubleTapAction(x, y);
if (action != ImageBuffer.DoubleTapAction.NOTHING)
return action;
}
return ImageBuffer.DoubleTapAction.NOTHING;
};
/**
* Possible double tap actions.
* @enum {number}
*/
ImageBuffer.DoubleTapAction = {
NOTHING: 0,
COMMIT: 1,
CANCEL: 2
};
/**
* ImageBuffer.Overlay is a pluggable extension that modifies the outlook
* and the behavior of the ImageBuffer instance.
* @constructor
* @struct
*/
ImageBuffer.Overlay = function() {};
/**
* Get Z index of this overlay.
* @return {number} Z index of this overlay.
*/
ImageBuffer.Overlay.prototype.getZIndex = function() { return 0; };
/**
* Draw an overlay.
*/
ImageBuffer.Overlay.prototype.draw = function() {};
/**
* Get cursor style.
* @param {number} x X coordinate for cursor.
* @param {number} y Y coordinate for cursor.
* @param {boolean} mouseDown If mouse button is down.
* @return {?string} A value for style.cursor CSS property or null for
* default.
*/
ImageBuffer.Overlay.prototype.getCursorStyle = function(x, y, mouseDown) {
return null;
};
/**
* Handle click.
* @param {number} x X coordinate.
* @param {number} y Y coordinate.
* @return {boolean} True if handled.
*/
ImageBuffer.Overlay.prototype.onClick = function(x, y) {
return false;
};
/**
* Returns a drag handler.
* @param {number} x Event X coordinate.
* @param {number} y Event Y coordinate.
* @param {boolean} touch True if it's a touch event, false if mouse.
* @return {?ImageBuffer.DragHandler} A function to be called on mouse drag.
*/
ImageBuffer.Overlay.prototype.getDragHandler = function(x, y, touch) {
return null;
};
/**
* Returns an action for a double tap.
* @param {number} x X coordinate.
* @param {number} y Y coordinate.
* @return {ImageBuffer.DoubleTapAction} Double tap action.
*/
ImageBuffer.Overlay.prototype.getDoubleTapAction = function(x, y) {
return ImageBuffer.DoubleTapAction.NOTHING;
};
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