Whenever the processing model described below causes one of these events to be fired, the event fired must use the DragEvent interface defined above, must have the bubbling and cancelable behaviors given in the table below, and must have the context information set up as described after the table, with the view attribute set to the view with which the user interacted to trigger the drag-and-drop event, the detail attribute set to zero, the mouse and key attributes set according to the state of the input devices as they would be for user interaction events, and the relatedTarget attribute set to null.
If there is no relevant pointing device, the object must have its screenX , screenY , clientX , clientY , and button attributes set to 0. The dataTransfer object's contents are empty except for dragstart events and drop events, for which the contents are set as described in the processing model, below.
The effectAllowed attribute must be set to " uninitialized " for dragstart events, and to whatever value the field had after the last drag-and-drop event was fired for all other events only counting events fired by the user agent for the purposes of the drag-and-drop model described below. The dropEffect attribute must be set to " none " for dragstart , drag , and dragleave events except when stated otherwise in the algorithms given in the sections below , to the value corresponding to the current drag operation for drop and dragend events, and to a value based on the effectAllowed attribute's value and to the drag-and-drop source, as given by the following table, for the remaining events dragenter and dragover :.
When the user attempts to begin a drag operation, the user agent must first determine what is being dragged. If the drag operation was invoked on a selection, then it is the selection that is being dragged. Otherwise, it is the first element, going up the ancestor chain, starting at the node that the user tried to drag, that has the DOM attribute draggable set to true. If there is no such element, then nothing is being dragged, the drag-and-drop operation is never started, and the user agent must not continue with this algorithm.
If the user agent determines that something can be dragged, a dragstart event must then be fired at the source node. The source node depends on the kind of drag and how it was initiated.
If it is a selection that is being dragged, then the source node is the node that the user started the drag on typically the text node that the user originally clicked. If the user did not specify a particular node, for example if the user just told the user agent to begin a drag of "the selection", then the source node is the deepest node that is a common ancestor of all parts of the selection.
If it is not a selection that is being dragged, then the source node is the element that is being dragged. Multiple events are fired on the source node during the course of the drag-and-drop operation.
The list of dragged nodes also depends on the kind of drag. If it is a selection that is being dragged, then the list of dragged nodes contains, in tree order , every node that is partially or completely included in the selection including all their ancestors. Otherwise, the list of dragged nodes contains only the source node.
If it is a selection that is being dragged, the dataTransfer member of the event must be created with no nodes. Otherwise, it must be created containing just the source node. Script can use the addElement method to add further elements to the list of what is being dragged. This list is only used for rendering the drag feedback. The dataTransfer member of the event also has data added to it, as follows:.
If files are being dragged, then the user agent must add the files to the dataTransfer member's files attribute's FileList object. Dragging files can only happen from outside a browsing context , for example from a file system manager application, and thus the dragstart event is actually implied in this case.
Let urls be an empty list of absolute URLs. If the event is canceled, then the drag-and-drop operation must not occur; the user agent must not continue with this algorithm. Since events with no event handlers registered are, almost by definition, never canceled, drag-and-drop is always available to the user if the author does not specifically prevent it. The drag-and-drop feedback must be generated from the first of the following sources that is available:.
The user agent must take a note of the data that was placed in the dataTransfer object. This data will be made available again when the drop event is fired.
From this point until the end of the drag-and-drop operation, device input events e. In addition, the user agent must track all DOM changes made during the drag-and-drop operation, and add them to its undo history as one atomic operation once the drag-and-drop operation has ended. During the drag operation, the element directly indicated by the user as the drop target is called the immediate user selection.
Only elements can be selected by the user; other nodes must not be made available as drop targets. However, the immediate user selection is not necessarily the current target element , which is the element currently selected for the drop part of the drag-and-drop operation.
The immediate user selection changes as the user selects different elements either by pointing at them with a pointing device, or by selecting them in some other way.
The current target element changes when the immediate user selection changes, based on the results of event handlers in the document, as described below. Both the current target element and the immediate user selection can be null, which means no target element is selected. They can also both be elements in other DOM-based documents, or other non-Web programs altogether.
For example, a user could drag text to a word-processor. The current target element is initially null. In addition, there is also a current drag operation , which can take on the values "none", "copy", "link", and "move". Initially, it has the value "none". It is updated by the user agent as described in the steps below. If the user agent is still performing the previous iteration of the sequence when the next iteration becomes due, the user agent must not execute the overdue iteration, effectively "skipping missed frames" of the drag-and-drop operation.
First, the user agent must fire a drag event at the source node. If this event is canceled, the user agent must set the current drag operation to none no drag operation. Next, if the drag event was not canceled and the user has not ended the drag-and-drop operation, the user agent must check the state of the drag-and-drop operation, as follows:.
First, if the user is indicating a different immediate user selection than during the last iteration or if this is the first iteration , and if this immediate user selection is not the same as the current target element , then the current target element must be updated, as follows:.
If the new immediate user selection is null, or is in a non-DOM document or application, then set the current target element to the same value. Otherwise, the user agent must fire a dragenter event at the immediate user selection. If the event is canceled, then the current target element must be set to the immediate user selection. Otherwise, if the current target element is not the body element , the user agent must fire a dragenter event at the body element , and the current target element must be set to the body element , regardless of whether that event was canceled or not.
If the body element is null, then the current target element would be set to null too in this case, it wouldn't be set to the Document object. If the previous step caused the current target element to change, and if the previous target element was not null or a part of a non-DOM document, the user agent must fire a dragleave event at the previous target element. If the current target element is a DOM element, the user agent must fire a dragover event at this current target element.
If the dragover event is not canceled, the current drag operation must be reset to "none". Otherwise, the current drag operation must be set based on the values the effectAllowed and dropEffect attributes of the dataTransfer object had after the event was handled, as per the following table:. Then, regardless of whether the dragover event was canceled or not, the drag feedback e.
Otherwise, if the current target element is not a DOM element, the user agent must use platform-specific mechanisms to determine what drag operation is being performed none, copy, link, or move. This sets the current drag operation.
Otherwise, if the user ended the drag-and-drop operation e. The user agent must execute the following steps, then stop looping. If the current drag operation is none no drag operation , or, if the user ended the drag-and-drop operation by canceling it e. If the current target element is a DOM element, the user agent must fire a dragleave event at it; otherwise, if it is not null, it must use platform-specific conventions for drag cancellation. Otherwise, the drag operation was as success.
If the current target element is a DOM element, the user agent must fire a drop event at it; otherwise, it must use platform-specific conventions for indicating a drop. When the target is a DOM element, the dropEffect attribute of the event's dataTransfer object must be given the value representing the current drag operation copy , link , or move , and the object must be set up so that the getData method will return the data that was added during the dragstart event, and the files attribute will return a FileList object with any files that were dragged.
If the event is canceled, the current drag operation must be set to the value of the dropEffect attribute of the event's dataTransfer object as it stood after the event was handled. Otherwise, the event is not canceled, and the user agent must perform the event's default action, which depends on the exact target as follows:. Finally, the user agent must fire a dragend event at the source node , with the dropEffect attribute of the event's dataTransfer object being set to the value corresponding to the current drag operation.
The current drag operation can change during the processing of the drop event, if one was fired. The event is not cancelable. After the event has been handled, the user agent must act as follows:.
The model described above is independent of which Document object the nodes involved are from; the events must be fired as described above and the rest of the processing model must be followed as described above, irrespective of how many documents are involved in the operation. If the drag is initiated in another application, the source node is not a DOM node, and the user agent must use platform-specific conventions instead when the requirements above involve the source node.
User agents in this situation must act as if the dragged data had been added to the DataTransfer object when the drag started, even though no dragstart event was actually fired; user agents must similarly use platform-specific conventions when deciding on what drag feedback to use. If a drag is started in a document but ends in another application, then the user agent must instead replace the parts of the processing model relating to handling the target according to platform-specific conventions.
In any case, scripts running in the context of the document must not be able to distinguish the case of a drag-and-drop operation being started or ended in another application from the case of a drag-and-drop operation being started or ended in another document from another domain. All HTML elements may have the draggable content attribute set. The draggable attribute is an enumerated attribute. It has three states. The first state is true and it has the keyword true. The second state is false and it has the keyword false.
The third state is auto ; it has no keywords but it is the missing value default. The true state means the element is draggable; the false state means that it is not. The auto state uses the default behavior of the user agent. Can be set, to override the default and set the draggable content attribute.
The draggable DOM attribute, whose value depends on the content attribute's in the way described below, controls whether or not the element is draggable.
Generally, only text selections are draggable, but elements whose draggable DOM attribute is true become draggable as well. If an element's draggable content attribute has the state true , the draggable DOM attribute must return true. Otherwise, if the element's draggable content attribute has the state false , the draggable DOM attribute must return false. Otherwise, the element's draggable content attribute has the state auto. If the element is an img element, or, if the element is an a element with an href content attribute, the draggable DOM attribute must return true.
Otherwise, the draggable DOM must return false. If the draggable DOM attribute is set to the value false, the draggable content attribute must be set to the literal value false. If the draggable DOM attribute is set to the value true, the draggable content attribute must be set to the literal value true. Copy-and-paste is a form of drag-and-drop: the "copy" part is equivalent to dragging content to another application the "clipboard" , and the "paste" part is equivalent to dragging content from another application.
Select-and-paste a model used by mouse operations in the X Window System is equivalent to a drag-and-drop operation where the source is the selection. When the user invokes a copy operation, the user agent must act as if the user had invoked a drag on the current selection.
If the drag-and-drop operation initiates, then the user agent must act as if the user had indicated as the immediate user selection a hypothetical application representing the clipboard. Then, the user agent must act as if the user had ended the drag-and-drop operation without canceling it. If the drag-and-drop operation didn't get canceled, the user agent should then follow the relevant platform-specific conventions for copy operations e.
When the user invokes a cut operation, the user agent must act as if the user had invoked a copy operation see the previous section , followed, if the copy was completed successfully, by a selection delete operation. When the user invokes a clipboard paste operation, the user agent must act as if the user had invoked a drag on a hypothetical application representing the clipboard, setting the data associated with the drag as the content on the clipboard in whatever formats are available.
Then, the user agent must act as if the user had indicated as the immediate user selection the element with the keyboard focus, and then ended the drag-and-drop operation without canceling it.
When the user invokes a selection paste operation, the user agent must act as if the user had invoked a drag on the current selection, then indicated as the immediate user selection the element with the keyboard focus, and then ended the drag-and-drop operation without canceling it.
User agents must not make the data added to the DataTransfer object during the dragstart event available to scripts until the drop event, because otherwise, if a user were to drag sensitive information from one document to a second document, crossing a hostile third document in the process, the hostile document could intercept the data.
For the same reason, user agents must consider a drop to be successful only if the user specifically ended the drag operation — if any scripts end the drag operation, it must be considered unsuccessful canceled and the drop event must not be fired. User agents should take care to not start drag-and-drop operations in response to script actions. For example, in a mouse-and-window environment, if a script moves a window while the user has his mouse button depressed, the UA would not consider that to start a drag.
This is important because otherwise UAs could cause data to be dragged from sensitive sources and dropped into hostile documents without the user's consent.
The undo transaction history is a list of entries. The entries are of two type: DOM changes and undo objects. Each DOM changes entry in the undo transaction history consists of batches of one or more of the following:.
Undo object entries consist of objects representing state that scripts running in the document are managing. For example, a Web mail application could use an undo object to keep track of the fact that a user has moved an e-mail to a particular folder, so that the user can undo the action and have the e-mail return to its former location. Broadly speaking, DOM changes entries are handled by the UA in response to user edits of form controls and editing hosts on the page, and undo object entries are handled by script in response to higher-level user actions such as interactions with server-side state, or in the implementation of a drawing tool.
This API sucks. It's a terrible API. Really bad. I hate it. Here are the requirements:. To manage undo object entries in the undo transaction history , the UndoManager interface can be used:. Returns the number of the current entry in the undo history. Entries at and past this point are redo entries.
UndoManager objects represent their document's undo transaction history. Only undo object entries are visible with this API, but this does not mean that DOM changes entries are absent from the undo transaction history. The length attribute must return the number of undo object entries in the undo transaction history.
This is the length. The object's indices of the supported indexed properties are the numbers in the range zero to length -1 , unless the length is zero, in which case there are no supported indexed properties. The item n method must return the n th undo object entry in the undo transaction history. The browser will report an error if no protocol such as http: is entered, or if the URL is otherwise malformed. On devices with dynamic keyboards, the default keyboard will often display some or all of the colon, period, and forward slash as default keys.
Note: Just because the URL is well-formed doesn't necessarily mean that it refers to a location that actually exists! This control looks like a text field but allows only floating-point numbers, and usually provides buttons in the form of a spinner to increase and decrease the value of the control.
On devices with dynamic keyboards, the numeric keyboard is generally displayed. With the number input type, you can constrain the minimum and maximum values allowed by setting the min and max attributes. You can also use the step attribute to set the increment increase and decrease caused by pressing the spinner buttons.
By default, the number input type only validates if the number is an integer. If omitted, the step value defaults to 1 , meaning only whole numbers are valid. Let's look at some examples. The first one below creates a number control whose value is restricted to any value between 1 and 10 , and whose increase and decrease buttons change its value by 2.
The second one creates a number control whose value is restricted to any value between 0 and 1 inclusive, and whose increase and decrease buttons change its value by 0. The number input type makes sense when the range of valid values is limited, for example a person's age or height.
If the range is too large for incremental increases to make sense such as USA ZIP codes, which range from to , the tel type might be a better option; it provides the numeric keypad while forgoing the number's spinner UI feature. Another way to pick a number is to use a slider. You see these quite often on sites like house buying sites where you want to set a maximum property price to filter by. Let's look at a live example to illustrate this:. Usage-wise, sliders are less accurate than text fields.
Therefore, they are used to pick a number whose precise value is not necessarily important. The slider-thumb can be moved via mouse or touch, or with the arrows of the keypad. It's important to properly configure your slider.
To that end, it's highly recommended that you set the min , max , and step attributes which set the minimum, maximum and increment values, respectively.
Let's look at the code behind the above example, so you can see how its done. The advantage of doing this is that you can guarantee that search engines will recognize the website because of having acceptable content. Web pages that get better indexing are very popular to most web portals and search engines push them higher to online searches. What is god about this development is that many users of Smart-Phone or Tablet can discover the great benefits when using their gadget.
Video and Audio Support: Regarding the past HTML versions, in order for the browsers to play audio and video files, most browsers require using. HTML5 is now giving us the convenience of utilizing other elements to play videos and audio files, which does not involve such plug-ins anymore. HTML5 clients enable users to access remote desktops and applications through a Web browser which lets them work from any device, anywhere. When HTML5 first emerged, the user experience needed some improvements, but now browsers use protocols that make it simple and easy to use.
It has become an everyday practice for companies to use a mix of Windows and Linux based applications combined with SaaS. The browser is something that links all these different devices together. Almost every device today is able to render HTML5.
0コメント