vimo-dt/lib/components/content/img-util.js

A Vue2.x UI Project For Mobile & HyBrid

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.updateImgs = updateImgs;
exports.sortTopToBottom = sortTopToBottom;
function updateImgs(imgs, viewableTop, contentHeight, scrollDirectionY, requestableBuffer, renderableBuffer) {
  var viewableBottom = viewableTop + contentHeight;
  var priority1 = [];
  var priority2 = [];
  var img = void 0;
  for (var i = 0, ilen = imgs.length; i < ilen; i++) {
    img = imgs[i];

    if (scrollDirectionY === 'up') {
      if (img.getTop() < viewableBottom && img.getBottom() > viewableTop - renderableBuffer) {
        img.canRequest = img.canRender = true;
        priority1.push(img);
        continue;
      }

      if (img.getBottom() <= viewableTop && img.getBottom() > viewableTop - requestableBuffer) {
        img.canRequest = true;
        img.canRender = false;
        priority2.push(img);
        continue;
      }

      if (img.getTop() >= viewableBottom && img.getTop() < viewableBottom + renderableBuffer) {
        img.canRequest = img.canRender = false;
        continue;
      }
    } else {
      if (img.getBottom() > viewableTop && img.getTop() < viewableBottom + renderableBuffer) {
        img.canRequest = img.canRender = true;
        priority1.push(img);
        continue;
      }

      if (img.getTop() >= viewableBottom && img.getTop() < viewableBottom + requestableBuffer) {
        img.canRequest = true;
        img.canRender = false;
        priority2.push(img);
        continue;
      }

      if (img.getBottom() <= viewableTop && img.getBottom() > viewableTop - renderableBuffer) {
        img.canRequest = img.canRender = false;
        continue;
      }
    }

    img.canRequest = img.canRender = false;
    img.reset();
  }

  priority1.sort(sortTopToBottom).forEach(function (i) {
    return i.update();
  });

  if (scrollDirectionY === 'up') {
    priority2.sort(sortTopToBottom).reverse().forEach(function (i) {
      return i.update();
    });
  } else {
    priority2.sort(sortTopToBottom).forEach(function (i) {
      return i.update();
    });
  }
}

function sortTopToBottom(a, b) {
  if (a.top < b.top) {
    return -1;
  }
  if (a.top > b.top) {
    return 1;
  }
  return 0;
}