In web programs, data is often retrieved from the server database and presented to users in the browser using various charts (line charts, cube charts, pie charts, and candle charts, this technology is widely used in business intelligence (BI) systems. The principle is as follows: 1. After a chart is generated on the server side, it is returned to the browser in the form of JPEG, PNG, and GIF images for display. Currently, jfreechart is used. 2. the browser loads the flash image display file (SWF), like the visual display control in MFC or VB. Currently, fusioncharts and openflashchart are used in this way, the charts generated in this way are cool. 3. the browser uses JavaScript for dynamic drawing. This method mainly depends on the <canvas> tag of HTML, and obtains the context for drawing through getcontext () of canvas (this concept is very similar to the device context DC in MFC ), then you can use moveTo (), fillrect ()
. Unfortunately, ie does not support this label, so the versatility is not very good. Fortunately, Google has developed an excanvas for us to solve the incompatibility problem. Currently, flot is used. 4. The <SVG> label (Scalable Vector) proposed by Adobe
Graphics), which can be embedded with labels for <rect>'s graphic definition. This method can be used to draw vector images, but there are also browser compatibility problems. 5. Using CSS to modify <div> and other labels can also make some simple but cool charts. Currently, fooplot, flowchart, and nceskids are used in this way. 6. Use Java applet to show that this is an elimination technology. Of course, Microsoft's Web Application Development camp should have other Chart display methods (net graphic display controls ?), However, there is basically no research, and I dare not do it here.
