src="interactivity.js"> > // 绘制图形 function drawCircle(x, y, r) { canvas.getContext('2d').fillStyle = 'red'; canvas.getContext('2d').fillRect(x r, y r, r, r); } // 绘制文本 function drawString(x, y, text, color) { canvas.getContext('2d').fillStyle = color; canvas.getContext('2d').fillText(text, x, y); } // 获取上下文元素 var context = idc.getContextgetContext('2d'); // 更新上下文元素 context.width = 400; context.height = 200; // 绘制图形 drawCircle(100, 100, 10); drawString("Hello World", 100, 100, "!");
``` 3. 一个带有事件处理和数据交互的模板: ```html
Canvas Web App
src="script.js">
src="data.js"> > // 获取数据 var data = idc.getData(); // 绘制数据 drawData(data); // 获取用户输入 function drawData(data) { var x = 100; var y = 100; var text = ""; for (var i = 0; i < data.length; i ) { text = data[i][0] "," data[i][1] " "; } canvas.getContext('2d').fillStyle = 'red'; canvas.getContext('2d').fillRect(x data[0][0], y data[0][1], data[0][0] 1, data[0][1] 1); canvas.getContext('2d').fillText(text, x, y); }