[英]Why fillText doesn't show up in canvas?
尝试将fillStyle颜色更改为许多不同的颜色,也更改了不同的位置,但一无所获。 控制台中也没有错误。 我已经在画布上绘制了图块和精灵,这和它有关系吗? 我只需要在每次按键时打印出简单的文本即可。
这是代码:
function move(e) {
if (e.keyCode == 39) {
boatPosX += 5;
view.x -= 5
moveCount++;
context.fillStyle = "red";
context.fillText(theArray[0].question, 0, 0);
console.log(theArray[0].question);
}
其余代码:
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var view = {x: 0, y: 0};
var questionsArray = [];
var moveCount = 0;
var mapArray = [
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 2, 2, 0],
[0, 0, 1, 1, 1, 0, 0, 2, 0, 0],
[0, 0, 1, 1, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 1, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 2, 2, 0],
[0, 0, 1, 1, 1, 0, 0, 2, 0, 0],
[0, 0, 1, 1, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
];
function isPositionWall(ptX, ptY) {
var gridX = Math.floor(ptX / 36)
var gridY = Math.floor(ptY / 36)
if(gridX < 0 || gridX >= mapArray[0].length)
return true;
if(gridY < 0 || gridY >= mapArray.length)
return true;
return mapArray[gridX][gridY];
}
var theArray = [];
var Question = function(question, answer1, answer2, correctAnswer) {
this.question = question;
this.answer1 = answer1;
this.answer2 = answer2;
this.correctAnswer = correctAnswer;
this.addToArray = function(){
theArray.push(this);
};
this.addToArray();
}
Question.prototype.checkAnswer = function() {
return answer1 || answer2 == correctAnswer;
}
var question1 = new Question("Taip ar ne?", "Taip", "Ne", "Taip");
var question2 = new Question("Jo ar ne?", "Ne", "Jo", "Jo");
var question3 = new Question("Aha ar ne?", "Aha", "Ne", "Ne");
var question4 = new Question("Ja ar ne?", "Taip", "Ne", "Taip");
var question5 = new Question("Jojo ar ne?", "Taip", "Ne", "Taip");
var question6 = new Question("Taip ar ne?", "Taip", "Ne", "Taip");
var question7 = new Question("Taip ar ne?", "Taip", "Ne", "Taip");
var StyleSheet = function(image, width, height, x, y) {
this.image = image;
this.width = width;
this.height = height;
this.x = x;
this.y = y
this.draw = function(image, sx, sy, swidth, sheight, x, y, width, height) {
context.drawImage(image, sx, sy, swidth, sheight, x, y, width, height);
};
this.drawimage = function(image, x, y, width, height) {
context.drawImage(image, x, y, width, height);
};
};
/* Initial Sprite Position */
var boatPosX = canvas.height/2 - 50;
var boatPosY = canvas.height/2 - 50;
function render(viewport) {
context.save();
context.translate(view.x, view.y);
requestAnimationFrame(render);
var oldPosX = boatPosX;
var oldPosY = boatPosY;
for (let i = 0; i < mapArray.length; i++) {
for (let j = 0; j < mapArray[i].length; j++) {
if (mapArray[i][j] == 0) {
this.sprite.draw(
background,
190,
230,
26,
26,
i * this.sprite.width,
j * this.sprite.height,
this.sprite.width,
this.sprite.height
);
}
if (mapArray[i][j] == 1) {
this.sprite.draw(
background,
30,
30,
26,
26,
i * this.sprite.width,
j * this.sprite.height,
this.sprite.width,
this.sprite.height
);
}
if (mapArray[i][j] == 2) {
this.sprite.draw(
background,
200,
20,
26,
26,
i * this.sprite.width,
j * this.sprite.height,
this.sprite.width,
this.sprite.height
);
}
}
}
this.ship.drawimage(boat, boatPosX, boatPosY, 50, 50);
//console.log(boatPosX + ship.width)
if(isPositionWall(boatPosX, boatPosY)) {
boatPosX = oldPosY;
console.log("collision");
}
context.restore();
};
function move(e) {
if (e.keyCode == 39) {
boatPosX += 5;
//canvas.width += 2;
view.x -= 5
moveCount++;
console.log(moveCount);
console.log("right");
context.fillStyle = "red";
context.fillText(theArray[0].question, 0, 0);
console.log(theArray[0].question);
}
if (e.keyCode == 37) {
boatPosX -= 5;
view.x += 5
moveCount++;
console.log(moveCount);
console.log("left");
}
if (e.keyCode == 38) {
boatPosY -= 5;
view.Y += 5
moveCount++;
console.log(moveCount);
console.log("up");
}
if (e.keyCode == 40) {
boatPosY += 5;
view.Y += 5
moveCount++;
console.log(moveCount);
console.log("down");
}
}
document.onkeydown = move;
var background = new Image();
background.src = "ground.png";
var sprite = new StyleSheet(background, 36, 36, 16, 16);
var boat = new Image();
boat.src = "ship.png";
var ship = new StyleSheet(boat, 90, 100, 16, 16);
console.log(Math.floor(boatPosX / 36));
console.log(mapArray[Math.floor(boatPosX / 36)]);
render();
似乎是因为您试图将文本设置为0,0。 默认情况下,文本将绘制在Y位置0上方(因此离开画布顶部,这就是为什么您什么都看不到的原因)。 如果将其设为0,10或0,20,则可能会看到一些文字。
可以像这样更改文本基准行,因此在0,0处您将看到一些内容。
context.textBaseline = "top";
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.