Javascript 使用pdf.js在画布中绘制矩形,并加载pdf文件
我正在尝试在pdf文件上绘制矩形。在pdf中绘制矩形时,矩形无法正确绘制 我想一次只画一个矩形,当我画新矩形时,旧矩形应该被删除,但它没有发生 这是我的密码: pdf渲染的渲染代码工作正常 鼠标移动功能无法正常工作 注 当我启用clearRect和putImageData函数时,矩形绘制正确,但画布pdf显示为空。这是附上的图片 当仅启用clearRect功能时,则在pdf中显示多个矩形。这是附上的图片Javascript 使用pdf.js在画布中绘制矩形,并加载pdf文件,javascript,pdf,canvas,pdf.js,Javascript,Pdf,Canvas,Pdf.js,我正在尝试在pdf文件上绘制矩形。在pdf中绘制矩形时,矩形无法正确绘制 我想一次只画一个矩形,当我画新矩形时,旧矩形应该被删除,但它没有发生 这是我的密码: pdf渲染的渲染代码工作正常 鼠标移动功能无法正常工作 注 当我启用clearRect和putImageData函数时,矩形绘制正确,但画布pdf显示为空。这是附上的图片 当仅启用clearRect功能时,则在pdf中显示多个矩形。这是附上的图片 请检查以下内容,在创建新矩形之前需要清除现有矩形 function renderPage(n
请检查以下内容,在创建新矩形之前需要清除现有矩形
function renderPage(num) {
pageRendering = true;
pdf.getPage(num).then(function (page) {
var viewport = page.getViewport({ scale: scale });
canvas.height = viewport.height;
canvas.width = viewport.width;
var renderContext = {
canvasContext: ctx,
viewport: viewport
};
var renderTask = page.render(renderContext);
renderTask.promise.then(function () {
pageRendering = false;
//You need to clear the existing rectangle
pdfPages[num] = ctx.getImageData(0, 0, canvas.width, canvas.height);
//Now you can draw new rectangle
drawRectangle(10, 10, 100, 50);
if (pageNumPending !== null) {
renderPage(pageNumPending);
pageNumPending = null;
}
});
});
function drawRectangle(x, y, w, h) {
ctx.strokeStyle = color;
ctx.strokeRect(x, y, w, h);
}
请检查以下内容,在创建新矩形之前需要清除现有矩形
function renderPage(num) {
pageRendering = true;
pdf.getPage(num).then(function (page) {
var viewport = page.getViewport({ scale: scale });
canvas.height = viewport.height;
canvas.width = viewport.width;
var renderContext = {
canvasContext: ctx,
viewport: viewport
};
var renderTask = page.render(renderContext);
renderTask.promise.then(function () {
pageRendering = false;
//You need to clear the existing rectangle
pdfPages[num] = ctx.getImageData(0, 0, canvas.width, canvas.height);
//Now you can draw new rectangle
drawRectangle(10, 10, 100, 50);
if (pageNumPending !== null) {
renderPage(pageNumPending);
pageNumPending = null;
}
});
});
function drawRectangle(x, y, w, h) {
ctx.strokeStyle = color;
ctx.strokeRect(x, y, w, h);
}
function renderPage(num) {
pageRendering = true;
pdf.getPage(num).then(function (page) {
var viewport = page.getViewport({ scale: scale });
canvas.height = viewport.height;
canvas.width = viewport.width;
var renderContext = {
canvasContext: ctx,
viewport: viewport
};
var renderTask = page.render(renderContext);
renderTask.promise.then(function () {
pageRendering = false;
//You need to clear the existing rectangle
pdfPages[num] = ctx.getImageData(0, 0, canvas.width, canvas.height);
//Now you can draw new rectangle
drawRectangle(10, 10, 100, 50);
if (pageNumPending !== null) {
renderPage(pageNumPending);
pageNumPending = null;
}
});
});
function drawRectangle(x, y, w, h) {
ctx.strokeStyle = color;
ctx.strokeRect(x, y, w, h);
}