Three.js开发实现3D地图的实践过程总结(6)

export function getPoiRect(poi, zoomLevel, wrapper) {
 let style = getStyle(poi.styleId, zoomLevel);
 if (!style) {
 console.warn("style is invalid!");
 return;
 }
 let labelStyle = getStyle(style.labelid, zoomLevel);
 if (!labelStyle) {
 console.warn("labelStyle is invalid!");
 return;
 }
 if (!poi.text) {
 return;
 }
 let charWidth = (TEXTPROP.charWidth || 11.2) * // 11.2是根据测试得到的估值
 (labelStyle.fontSize / (TEXTPROP.fontSize || 13)); // 13是得到11.2时的fontSize
 // 返回2d坐标
 let x = 0;//poi.points[0].x;
 let y = 0;//-poi.points[0].z;
 let path = [];
 let icon = iconSet[poi.styleId];
 let iconWidh = (icon && icon.width) || 32;
 let iconHeight = (icon && icon.height) || 32;
 let multi = /\//g;
 let firstLinePos = [];
 let textAlign = null;
 let baseLine = null;
 let hOffset = (iconWidh / 2) * ICONSCALE;
 let vOffset = (iconHeight / 2) * ICONSCALE;
 switch(poi.direct) {
 case 2: { // 左
 firstLinePos.push(x - hOffset - 2);
 firstLinePos.push(y);
 textAlign = 'right';
 baseLine = 'middle';
 break;
 };
 case 3: { // 下
 firstLinePos.push(x);
 firstLinePos.push(y - vOffset - 2);
 textAlign = 'center';
 baseLine = 'top';
 break;
 };
 case 4: { // 上
 firstLinePos.push(x);
 firstLinePos.push(y + vOffset + 2);
 textAlign = 'center';
 baseLine = 'bottom';
 break;
 };
 case 1:{ // 右
 firstLinePos.push(x + hOffset + 2);
 firstLinePos.push(y);
 textAlign = 'left';
 baseLine = 'middle';
 break;
 };
 default: {
 firstLinePos.push(x);
 firstLinePos.push(y);
 textAlign = 'center';
 baseLine = 'middle';
 }
 }
 path = path.concat(firstLinePos);

 let minX = null, maxX = null;
 let minY = null, maxY = null;
 let parts = poi.text.split(multi);

 let textWidth = 0;
 if (wrapper) {
 // 汉字和数字的宽度是不同的，所以必须使用measureText来精确测量
 let textWidth1 = wrapper.context.measureText(parts[0]).width;
 let textWidth2 = wrapper.context.measureText(parts[1] || '').width;
 textWidth = Math.max(textWidth1, textWidth2);
 } else {
 textWidth = Math.max(parts[0].length, parts[1] ? parts[1].length : 0) * charWidth;
 }

 if (textAlign === 'left') {
 minX = x - hOffset;
 maxX = path[0] + textWidth; // 只用第一行文本
 } else if (textAlign === 'right') {
 minX = path[0] - textWidth;
 maxX = x + hOffset;
 } else { // center
 minX = x - Math.max(textWidth / 2, hOffset);
 maxX = x + Math.max(textWidth / 2, hOffset);
 }
 if (baseLine === 'top') {
 maxY = y + vOffset;
 minY = y - vOffset - labelStyle.fontSize * parts.length;
 } else if (baseLine === 'bottom') {
 maxY = y + vOffset + labelStyle.fontSize * parts.length;
 minY = y - vOffset;
 } else { // middle
 minY = Math.min(y - vOffset, path[1] - labelStyle.fontSize / 2);
 maxY = Math.max(y + vOffset, path[1] + labelStyle.fontSize * (parts.length + 0.5 - 1));
 }

 return {
 min: {
 x: minX,
 y: minY
 },
 max: {
 x: maxX,
 y: maxY
 }
 };
}