[英]Need help in displaying selection handles on rectangle using javascript
我想在代碼中添加一些內容,以便在繪制后選擇圖像(選擇處理程序應出現在角落和邊緣中間),然后拖動或增加/減小高度和寬度?
我的示例代碼在小提琴中,在這里,我正在使用鼠標事件處理程序繪制一個矩形。 我想選擇矩形並使用選擇處理程序來修改/更改它,而不是再次繪制它。
單擊“ ROI,度量”按鈕,然后可以使用鼠標事件進行繪制。
var oImageBuffer = document.createElement('img');
var oCanvas=document.getElementById("SetupImageCanvas");
var o2DContext=oCanvas.getContext("2d");
var oRect = {};
var oROI = {};
var oMetrics ={};
var oLayers = new Array();
var bDragging = false;
var bSetROI = false;
var bSetLayers = false;
InitMouseEvents();
var oSelect = document.getElementById("ImageList");
oSelect.onchange=function() {
changeCanvasImage(oSelect[oSelect.selectedIndex].value);
}
// Canvas event handlers (listeners).
function InitMouseEvents() {
oCanvas.addEventListener('mousedown', MouseDownEvent, false);
oCanvas.addEventListener('mouseup', MouseUpEvent, false);
oCanvas.addEventListener('mousemove', MouseMoveEvent, false);
oCanvas.addEventListener('mouseout', MouseOutEvent, false);
}
function MouseDownEvent(e) {
oRect.startX = e.pageX - this.offsetLeft;
oRect.startY = e.pageY - this.offsetTop;
bDragging = true;
}
function MouseUpEvent() {
bDragging = false;
}
function MouseOutEvent() {
document.getElementById("MouseCoords").innerHTML="";
}
function MouseMoveEvent(e) {
if (bDragging) {
oRect.w = (e.pageX - this.offsetLeft) - oRect.startX;
oRect.h = (e.pageY - this.offsetTop) - oRect.startY;
oCanvas.getContext('2d').clearRect(0,0,oCanvas.width, oCanvas.height);
var oROI = document.getElementById("btnROI");
if (oROI.checked) {
SetROI();
}
var oLayer = document.getElementById("btnLAYER");
if (oLayer.checked) {
SetLayer();
}
var oMetrics = document.getElementById("btnMetrics");
if (oMetrics.checked) {
SetMetrics();
}
}
if (bSetROI) {
DrawROI();
}
if (bSetLayers) {
DrawLayers();
}
if(bSetMetrics){
DrawMetrics();
}
// Display the current mouse coordinates.
ShowCoordinates(e);
}
function ShowCoordinates(e) {
x=e.clientX;
y=e.clientY;
document.getElementById("MouseCoords").innerHTML="(" + x + "," + y + ") " + document.getElementById('txtPatchCount').value;
}
// Interactively draw ROI rectangle(s) on the canvas.
function SetROI() {
bSetROI = true;
oROI.startX = oRect.startX;
oROI.startY = oRect.startY;
oROI.w = oRect.w;
oROI.h = oRect.h;
}
function DrawROI() {
o2DContext.lineWidth=1.5;
o2DContext.strokeStyle = '#0F0';
o2DContext.strokeRect(oROI.startX, oROI.startY, oROI.w, oROI.h);
var iPatches = document.getElementById('txtPatchCount').value;
o2DContext.beginPath();
var iTop = oROI.startY;
var iBottom = oROI.startY + oROI.h;
var iLeft = oROI.startX;
var iX = iLeft;
for (var iPatch=1; iPatch<iPatches; ++iPatch) {
iX = iLeft + iPatch*oROI.w/iPatches;
o2DContext.moveTo(iX, iTop);
o2DContext.lineTo(iX, iBottom);
}
o2DContext.lineWidth=0.25;
o2DContext.stroke();
}
function SetMetrics() {
bSetMetrics = true;
oMetrics.startX = oRect.startX;
oMetrics.startY = oRect.startY;
oMetrics.w = oRect.w;
oMetrics.h = oRect.h;
}
function DrawMetrics(){
o2DContext.strokeStyle = 'black';
o2DContext.strokeRect(oMetrics.startX, oMetrics.startY, oMetrics.w, oMetrics.h);
o2DContext.beginPath();
var iTop = oMetrics.startY;
var iBottom = oMetrics.startY + oMetrics.h;
var iLeft = oMetrics.startX;
var iX = iLeft;
o2DContext.moveTo(iX, iTop);
o2DContext.lineTo(iX, iBottom);
o2DContext.stroke();
}
// Interactively draw layer boundaries on the canvas.
function SetLayer() {
bSetLayers = true;
oLayers.length = 0;
oLayers.push(oRect.startY);
oLayers.push(oRect.startY + oRect.h);
}
function DrawLayers() {
o2DContext.lineWidth=0.25;
o2DContext.strokeStyle = '#F00';
o2DContext.beginPath();
var iY = oLayers[0];
var iLeft = 0;
var iRight = oCanvas.width;
for (var iLayer=0; iLayer<oLayers.length; ++iLayer) {
iY = oLayers[iLayer];
o2DContext.moveTo(iLeft, iY);
o2DContext.lineTo(iRight, iY);
o2DContext.stroke();
}
}
下面的博客正在做同樣的事情,但是我不確定如何在我的代碼中添加此功能。
http://simonsarris.com/blog/225-canvas-selecting-resizing-shape
請指導我如何在我的產品中添加相同的產品。
非常感謝您的幫助。
嘗試以下鏈接。 它正在做您想實現的目標。
http://simonsarris.com/blog/225-canvas-selecting-resizing-shape
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