Macharia ya Kifungaji ya Macharia ya Canvas

Mwaka wa tatu - Kutoa kipinde cha kipindi

Kipindi cha saa chafu kina kipinde. Kumekisha kipengele cha JavaScript kutoa kipinde cha kipindi:

JavaScript:

function drawClock() {
  drawFace(ctx, radius);
  drawNumbers(ctx, radius);
  drawTime(ctx, radius);
}
function drawTime(ctx, radius) {
  const now = new Date();
  let hour = now.getHours();
  let minute = now.getMinutes();
  let second = now.getSeconds();
  // saa
  hour = hour%12;
  hour = (hour*Math.PI/6)+(minute*Math.PI/(6*60))+(second*Math.PI/(360*60));
  drawHand(ctx, hour, radius*0.5, radius*0.07);
  // dakika
  minute = (minute*Math.PI/30)+(second*Math.PI/(30*60));
  drawHand(ctx, minute, radius*0.8, radius*0.07);
  // Sekunde
  second = (second*Math.PI/30);
  drawHand(ctx, second, radius*0.9, radius*0.02);
}
function drawHand(ctx, pos, length, width) {
  ctx.beginPath();
  ctx.lineWidth = width;
  ctx.lineCap = "round";
  ctx.moveTo(0,0);
  ctx.rotate(pos);
  ctx.lineTo(0, -length);
  ctx.stroke();
  ctx.rotate(-pos);
}

Jifunze kufanya kwako

Kueleza kipindi cha programu

Kumekisha kipengele cha Date kuupata saa, dakika na sekunde:

const now = new Date();
let hour = now.getHours();
let minute = now.getMinutes();
let second = now.getSeconds();

Kuandaa uangalifu wa kipinde cha saa, na kuandika uwezo wake (raia ya radius 50%) na uwezo (raia ya radius 7%):

hour = hour%12;
hour = (hour*Math.PI/6)+(minute*Math.PI/(6*60))+(second*Math.PI/(360*60));
drawHand(ctx, hour, radius*0.5, radius*0.07);

Tumia teknolojia yanaofanana kuandika kipinde cha saa na kipinde cha sekunde.

kitu ya drawHand() haukubaliwa. Iliandika ni mstari wa ujumbe na uwezo.

另请参阅：

CodeW3C.com 的完整 Canvas 参考手册