62 lines
1.8 KiB
JavaScript
62 lines
1.8 KiB
JavaScript
// Global object to hold drag information.
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var dragObj = new Object();
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dragObj.zIndex = 0;
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function drag(event, id) {
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var x, y;
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// If an element id was given, find it. Otherwise use the element being
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// clicked on.
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if (id)
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dragObj.elNode = document.getElementById(id);
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else {
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dragObj.elNode = event.target;
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// If this is a text node, use its parent element.
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if (dragObj.elNode.nodeType == 3)
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dragObj.elNode = dragObj.elNode.parentNode;
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}
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// Get cursor position with respect to the page.
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x = event.clientX + window.scrollX;
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y = event.clientY + window.scrollY;
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// Save starting positions of cursor and element.
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dragObj.cursorStartX = x;
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dragObj.cursorStartY = y;
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dragObj.elStartLeft = parseInt(dragObj.elNode.style.left, 10);
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dragObj.elStartTop = parseInt(dragObj.elNode.style.top, 10);
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if (isNaN(dragObj.elStartLeft)) dragObj.elStartLeft = 0;
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if (isNaN(dragObj.elStartTop)) dragObj.elStartTop = 0;
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// Update element's z-index.
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dragObj.elNode.style.zIndex = ++dragObj.zIndex;
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// Capture mousemove and mouseup events on the page.
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document.addEventListener("mousemove", dragGo, true);
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document.addEventListener("mouseup", dragStop, true);
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event.preventDefault();
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}
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function dragGo(event) {
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var x, y;
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// Get cursor position with respect to the page.
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x = event.clientX + window.scrollX;
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y = event.clientY + window.scrollY;
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// Move drag element by the same amount the cursor has moved.
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dragObj.elNode.style.left =
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(dragObj.elStartLeft + x - dragObj.cursorStartX) + "px";
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dragObj.elNode.style.top =
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(dragObj.elStartTop + y - dragObj.cursorStartY) + "px";
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event.preventDefault();
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}
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function dragStop(event) {
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// Stop capturing mousemove and mouseup events.
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document.removeEventListener("mousemove", dragGo, true);
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document.removeEventListener("mouseup", dragStop, true);
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}
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