From daa866a196962beb6171f847bd6f691f3ae38300 Mon Sep 17 00:00:00 2001 From: Topi Reinio Date: Fri, 11 Nov 2016 09:47:57 +0100 Subject: StocQt example: Prefetch values for stock list model Instead of doing a network request for each item in the stock list, prefetch values for all entries when creating the model. This improves performance when scrolling the list. Task-number: QTBUG-56114 Change-Id: I12f0012ec0a97f2bf03b53a5b51076171cd7fc7a Reviewed-by: Venugopal Shivashankar --- .../quick/demos/stocqt/content/StockListModel.qml | 66 ++++++++++++++++++++++ .../quick/demos/stocqt/content/StockListView.qml | 60 -------------------- 2 files changed, 66 insertions(+), 60 deletions(-) diff --git a/examples/quick/demos/stocqt/content/StockListModel.qml b/examples/quick/demos/stocqt/content/StockListModel.qml index be00e7bb1c..9b48124bda 100644 --- a/examples/quick/demos/stocqt/content/StockListModel.qml +++ b/examples/quick/demos/stocqt/content/StockListModel.qml @@ -42,6 +42,72 @@ import QtQuick 2.0 ListModel { id: stocks + + // pre-fetch data for all entries + Component.onCompleted: { + for (var idx = 0; idx < count; ++idx) { + getCloseValue(idx) + } + } + + function requestUrl(stockId) { + var endDate = new Date(""); // today + var startDate = new Date() + startDate.setDate(startDate.getDate() - 5); + + var request = "http://ichart.finance.yahoo.com/table.csv?"; + request += "s=" + stockId; + request += "&g=d"; + request += "&a=" + startDate.getMonth(); + request += "&b=" + startDate.getDate(); + request += "&c=" + startDate.getFullYear(); + request += "&d=" + endDate.getMonth(); + request += "&e=" + endDate.getDate(); + request += "&f=" + endDate.getFullYear(); + request += "&g=d"; + request += "&ignore=.csv"; + return request; + } + + function getCloseValue(index) { + var req = requestUrl(get(index).stockId); + + if (!req) + return; + + var xhr = new XMLHttpRequest; + + xhr.open("GET", req, true); + + xhr.onreadystatechange = function() { + if (xhr.readyState === XMLHttpRequest.LOADING || xhr.readyState === XMLHttpRequest.DONE) { + var records = xhr.responseText.split('\n'); + if (records.length > 0 && xhr.status == 200) { + var r = records[1].split(','); + var today = parseFloat(r[4]); + setProperty(index, "value", today.toFixed(2)); + + r = records[2].split(','); + var yesterday = parseFloat(r[4]); + var change = today - yesterday; + if (change >= 0.0) + setProperty(index, "change", "+" + change.toFixed(2)); + else + setProperty(index, "change", change.toFixed(2)); + + var changePercentage = (change / yesterday) * 100.0; + if (changePercentage >= 0.0) + setProperty(index, "changePercentage", "+" + changePercentage.toFixed(2) + "%"); + else + setProperty(index, "changePercentage", changePercentage.toFixed(2) + "%"); + } else { + var unknown = "n/a"; + set(index, {"value": unknown, "change": unknown, "changePercentage": unknown}); + } + } + } + xhr.send() + } // Uncomment to test invalid entries // ListElement {name: "The Qt Company"; stockId: "TQTC"; value: "999.0"; change: "0.0"; changePercentage: "0.0"} diff --git a/examples/quick/demos/stocqt/content/StockListView.qml b/examples/quick/demos/stocqt/content/StockListView.qml index 59f36b42cc..d2bd52a69d 100644 --- a/examples/quick/demos/stocqt/content/StockListView.qml +++ b/examples/quick/demos/stocqt/content/StockListView.qml @@ -64,65 +64,6 @@ Rectangle { model: StockListModel{} currentIndex: -1 // Don't pre-select any item - function requestUrl(stockId) { - var endDate = new Date(""); //today - var startDate = new Date() - startDate.setDate(startDate.getDate() - 5); - - var request = "http://ichart.finance.yahoo.com/table.csv?"; - request += "s=" + stockId; - request += "&g=d"; - request += "&a=" + startDate.getMonth(); - request += "&b=" + startDate.getDate(); - request += "&c=" + startDate.getFullYear(); - request += "&d=" + endDate.getMonth(); - request += "&e=" + endDate.getDate(); - request += "&f=" + endDate.getFullYear(); - request += "&g=d"; - request += "&ignore=.csv"; - return request; - } - - function getCloseValue(index) { - var req = requestUrl(model.get(index).stockId); - - if (!req) - return; - - var xhr = new XMLHttpRequest; - - xhr.open("GET", req, true); - - xhr.onreadystatechange = function() { - if (xhr.readyState === XMLHttpRequest.LOADING || xhr.readyState === XMLHttpRequest.DONE) { - var records = xhr.responseText.split('\n'); - if (records.length > 0 && xhr.status == 200) { - var r = records[1].split(','); - var today = parseFloat(r[4]); - model.setProperty(index, "value", today.toFixed(2)); - - r = records[2].split(','); - var yesterday = parseFloat(r[4]); - var change = today - yesterday; - if (change >= 0.0) - model.setProperty(index, "change", "+" + change.toFixed(2)); - else - model.setProperty(index, "change", change.toFixed(2)); - - var changePercentage = (change / yesterday) * 100.0; - if (changePercentage >= 0.0) - model.setProperty(index, "changePercentage", "+" + changePercentage.toFixed(2) + "%"); - else - model.setProperty(index, "changePercentage", changePercentage.toFixed(2) + "%"); - } else { - var unknown = "n/a"; - model.set(index, {"value": unknown, "change": unknown, "changePercentage": unknown}); - } - } - } - xhr.send() - } - onCurrentIndexChanged: { if (currentItem) { root.currentStockId = model.get(currentIndex).stockId; @@ -175,7 +116,6 @@ Rectangle { horizontalAlignment: Text.AlignRight verticalAlignment: Text.AlignVCenter text: value - Component.onCompleted: view.getCloseValue(index); } Text { -- cgit v1.2.3