(Make sure the page is selected in the Files workspace before you run it.) Save the file and run the page in a browser. If the user didn't pick an image or if this is the first time the page is displayed, the element isn't even rendered. If the user made a selection, imagePath contains the path.
To prevent this, you put the element in an if block that tests to see whether the imagePath variable has anything in it. This would normally mean that the src attribute would be empty and the image would show up as a red "x" (or whatever the browser renders when it can't find an image). The first time that the page runs, though, there's no image to display, because the user hasn't selected anything. Instead, it's set to meaning that it gets its value from the path you set in code. The src attribute isn't set to a file name or URL, like you'd do to display a static element.
In the body, there's also an element that's used to display the image that the user picked. The path is stored in variable named imagePath that you'll need later in the page. (If you tried to construct a path but there was nothing in Request, you'd get an error.) This results in a relative path like this: If there is, you construct a path for the image that consists of the name of the folder for the images and the user's image file name. You first see if there's a selection at all. In the code, you can get the user's selection (in other words, the image file name) from the list by reading Request. jpg file name when the page is submitted. Essentially, the list lets the user select a friendly name like "Photo 1", and it then passes the. The list has three options, and the value attribute of each list option has the name of one of the images that you put in the images folder. The body of the page has a drop-down list (a element) that's named photoChoice. Replace the existing content in the page with the following: var imagePath= "" Verify that the four images are not marked as read-only. (You won't use Photo4.jpg in this procedure, but you'll use it later in the article.) (Any images you have handy will do, but they should fit onto a page.) Rename the images Photo1.jpg, Photo2.jpg, Photo3.jpg, and Photo4.jpg. In the root folder of the website, add a new folder and name it images.Īdd four images to the images folder you just created. They select the name of the image from a drop-down list, and when they submit the page, the image they selected is displayed.Īdd a new page named DynamicImage.cshtml.
#Best image format for web loading how to
The procedure in this section shows how to display an image on the fly where users specify the image file name from a list of image names.
Sometimes, though, you need to be able to display images dynamically - that is, you don't know what image to display until the page is running. If an image is already available on your site and you just want to display it on a page, you use an HTML element like this: You can also let users upload images, which might be useful for tasks like letting them add a profile photo. You can add images to your website and to individual pages while you're developing the website. This tutorial also works with WebMatrix 3.Īdding an Image to a Web Page Dynamically The Path object, which provides methods that let you manipulate path and file names.These are the ASP.NET programming features introduced in the article: How to add an image to a page dynamically.This article shows you how to add, display, and manipulate images (resize, flip, and add watermarks) in an ASP.NET Web Pages (Razor) website.