【移动应用开发技术】Android如何实现系统打印功能

【移动应用开发技术】Android如何实现系统打印功能

这篇文章给大家分享的是有关Android如何实现系统打印功能的内容。在下觉得挺实用的，因此分享给大家做个参考，一起跟随在下过来看看吧。具体内容如下一、打印图片使用PrintHelper类，如：private

void

doPhotoPrint()

{

PrintHelper

photoPrinter

=

new

PrintHelper(getActivity());

photoPrinter.setScaleMode(PrintHelper.SCALE_MODE_FIT);

Bitmap

bitmap

=

BitmapFactory.decodeResource(getResources(),

R.drawable.droids);

photoPrinter.printBitmap("droids.jpg

-

test

print",

bitmap);

}可以在应用的菜单栏中调用该方法，当printBitmap()方法调用时，Android系统的打印界面会弹出，用户可以设置一些参数，然后进行打印或取消。二、打印自定义文档1.连接到PrintManager类：private

void

doPrint()

{

//

Get

a

PrintManager

instance

PrintManager

printManager

=

(PrintManager)

getActivity()

.getSystemService(Context.PRINT_SERVICE);

//

Set

job

name,

which

will

be

displayed

in

the

print

queue

String

jobName

=

getActivity().getString(R.string.app_name)

+

"

Document";

//

Start

a

print

job,

passing

in

a

PrintDocumentAdapter

implementation

//

to

handle

the

generation

of

a

print

document

printManager.print(jobName,

new

MyPrintDocumentAdapter(getActivity()),

null);

//

}注：print函数第二个参数为继承了抽象类PrintDocumentAdapter的适配器类，第三个参数为PrintAttributes对象，可以用来设置一些打印时的属性。2.创建打印适配器类打印适配器与Android系统的打印框架进行交互，处理打印的生命周期方法。打印过程主要有以下生命周期方法：onStart():当打印过程开始的时候调用；onLayout():当用户更改打印设置导致打印结果改变时调用，如更改纸张尺寸，纸张方向等；onWrite():当将要打印的结果写入到文件中时调用，该方法在每次onLayout（）调用后会调用一次或多次；onFinish()：当打印过程结束时调用。注：关键方法有onLayout()和onWrite()，这些方法默认都是在主线程中调用，因此如果打印过程比较耗时，应该在后台线程中进行。3.覆盖onLayout()方法在onLayout()方法中，你的适配器需要告诉系统框架文本类型，总页数等信息，如：@Override

public

void

onLayout(PrintAttributes

oldAttributes,

PrintAttributes

newAttributes,

CancellationSignal

cancellationSignal,

LayoutResultCallback

callback,

Bundle

metadata)

{

//

Create

a

new

PdfDocument

with

the

requested

page

attributes

mPdfDocument

=

new

PrintedPdfDocument(getActivity(),

newAttributes);

//

Respond

to

cancellation

request

if

(cancellationSignal.isCancelled()

)

{

callback.onLayoutCancelled();

return;

}

//

Compute

the

expected

number

of

printed

pages

int

pages

=

computePageCount(newAttributes);

if

(pages

>

0)

{

//

Return

print

information

to

print

framework

PrintDocumentInfo

info

=

new

PrintDocumentInfo

.Builder("print_output.pdf")

.setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)

.setPageCount(pages);

.build();

//

Content

layout

reflow

is

complete

callback.onLayoutFinished(info,

true);

}

else

{

//

Otherwise

report

an

error

to

the

print

framework

callback.onLayoutFailed("Page

count

calculation

failed.");

}

}注：onLayout（）方法的执行有完成，取消，和失败三种结果，你必须通过调用PrintDocumentAdapter.LayoutResultCallback类的适当回调方法表明执行结果，onLayoutFinished()方法的布尔型参数指示布局内容是否已经改变。onLayout()方法的主要任务就是计算在新的设置下，需要打印的页数，如通过打印的方向决定页数：

private

int

computePageCount(PrintAttributes

printAttributes)

{

int

itemsPerPage

=

4;

//

default

item

count

for

portrait

mode

MediaSize

pageSize

=

printAttributes.getMediaSize();

if

(!pageSize.isPortrait())

{

//

Six

items

per

page

in

landscape

orientation

itemsPerPage

=

6;

}

//

Determine

number

of

print

items

int

printItemCount

=

getPrintItemCount();

return

(int)

Math.ceil(printItemCount

/

itemsPerPage);

}4.覆盖onWrite()方法当需要将打印结果输出到文件中时，系统会调用onWrite（）方法，该方法的参数指明要打印的页以及结果写入的文件，你的方法实现需要将页面的内容写入到一个多页面的PDF文档中，当这个过程完成时，需要调用onWriteFinished()方法，如：@Override

public

void

onWrite(final

PageRange[]

pageRanges,

final

ParcelFileDescriptor

destination,

final

CancellationSignal

cancellationSignal,

final

WriteResultCallback

callback)

{

//

Iterate

over

each

page

of

the

document,

//

check

if

it's

in

the

output

range.

for

(int

i

=

0;

i

<

totalPages;

i++)

{

//

Check

to

see

if

this

page

is

in

the

output

range.

if

(containsPage(pageRanges,

i))

{

//

If

so,

add

it

to

writtenPagesArray.

writtenPagesArray.size()

//

is

used

to

compute

the

next

output

page

index.

writtenPagesArray.append(writtenPagesArray.size(),

i);

PdfDocument.Page

page

=

mPdfDocument.startPage(i);

//

check

for

cancellation

if

(cancellationSignal.isCancelled())

{

callback.onWriteCancelled();

mPdfDocument.close();

mPdfDocument

=

null;

return;

}

//

Draw

page

content

for

printing

drawPage(page);

//

Rendering

is

complete,

so

page

can

be

finalized.

mPdfDocument.finishPage(page);

}

}

//

Write

PDF

document

to

file

try

{

mPdfDocument.writeTo(new

FileOutputStream(

destination.getFileDescriptor()));

}

catch

(IOException

e)

{

callback.onWriteFailed(e.toString());

return;

}

finally

{

mPdfDocument.close();

mPdfDocument

=

null;

}

PageRange[]

writtenPages

=

computeWrittenPages();

//

Signal

the

print

framework

the

document

is

complete

callback.onWriteFinished(writtenPages);

...

}drawPage()方法实现：private

void

drawPage(PdfDocument.Page

page)

{

Canvas

canvas

=

page.getCanvas();

//

units

are

in

points

(1/72

of

an

inch)

int

titleBaseLine

=

72;

int

leftMargin

=

54;

Paint

paint

=

new

Paint();

paint.setColor(Color.BLACK);

paint.setTextSize(36);

canvas.drawText("Test

Title",

leftMargin,

titleBaseLine,

paint);

paint.setTe